on cubital joint; e, corresponding portion of palpus of Colotes atropos Walck., shewing different form of same apophysis in that species; d, abdomen of C. atropos, shewing difference from that of C. pabulator; f, natural length of the latter

spider.

3. Theridion Blackwallii Cambr., a, spider (female), enlarged; b, ditto in profile without

legs; c, profile without legs.

4. Enoplognatha caricis Fickert, a, spider (female) enlarged; b, ditto in profile without legs; c,

digital joint of palpus; d, natural

length.

5. Tmeticus Warburtonii sp. n., a, male enlarged; b, female ditto; c, female in profile without legs; d, palpus of male; d', portion of ditto, shewing characteristic bristles on prominence at base of the digital joint; j, k, portions of palpus of Tmeticus scopiger Menge, shewing difference in corresponding bristles in that species; g, abdomen of T. scopiger (female) in profile, shewing different form and direction of genital process from that of T. Warburtonii; e, nat. length of T. Warburtonii (male); f, ditto of

female.

6. Walckenäera interjecta Cambr., a, male enlarged; b,

profile of cephalothorax without

legs; c, palpus; d, natural length.

7. Walckenäera capito Westr., a, male enlarged; b, profile

without legs; c, portion of caput

from above and behind, shewing eminences and eyes; d, ditto from

in front; e, palpus; f, natural length.

8. Hyctia Nivoyi Luc., a, male enlarged; b, female ditto; c, male in profile without legs; d,

male, natural length; e, female

ditto.

9. Pellenes tripunctatus Walck., a, male enlarged; b, profile without legs; c, natural length.

On a New British Clorm, Allurns

Tetraedrus.

By FREDERICK O. P. CAMBRIDGE, B.A.

HE occurrence of any new form of animal life is always interesting, more especially in such a well worked and circumscribed area as that of Great Britain. Nevertheless it seems somewhat difficult to become very much elated over the discovery of a new species of earthworm, because worms are usually regarded as almost the lowest form in the scale of creation, and are not remarkable either for diversity of form, beauty of colouring, or for any particular intelligence displayed in the carrying out of those functions which are necessary to their existence.

The late Mr. Charles Darwin has, however, given a much greater interest to the study of the modest worm. In his work on earthworms and vegetable mould he has shown that the whole of the surface soil of our earth has passed and is continually passing through the bodies of earthworms. This one fact will prove how important a factor the worm is in determining the conformation of the surface of the earth.

So much for worms in general!

The discovery of that particular worm which has given occasion to the writing of this paper was not due to a love of worms innate

in the discoverer. Agreeably to the invitation of Dr. Benham, of University College, London, published in the Field newspaper, we forwarded parcels of worms for his inspection and determination. Amongst these were some small worms, about an inch in length, found beneath the stones of the gravelly bed of a stream at Hyde, near Bloxworth. These proved to be of a different genus to the ordinary earthworm, the genus and species not having, up till then, been recorded as occurring in Great Britain. As Dr. Benham wished to ascertain whether they were really aquatic worms or not, we took some trouble in determining exactly where and under what conditions this interesting worm occurred, with the result that the worm was pronounced semi-aquatic. It always occurred below high water mark, and seemed in no way inconvenienced when totally submerged, as we often found them under the stones 3 or 4 inches below the surface.

The position

The name of this worm is " Allurus tetraedrus.” of the four pairs of bristles with which each segment is provided and the position of the genital organs seem to be chief points to be noticed in determining the genus and species. Another small worm, "Allolobophora Boëckii," was found in some abundance in the wet bed of a marshy swamp at Morden Park. These, too, are interesting from the fact that the bristles, instead of being arranged in four pairs, are arranged as eight almost equidistant and single bristles. Those of the ordinary worm, "Lumbricus terrestris," are in four pairs, and confined to the ventral surface. Those of "Allurus tetraedrus" are in four equidistant pairs, each pair forming the angle of a square when viewed in transverse sections. (See diagrams.)

The aquatic worm, "Allurus tetraedrus," was found, soon after its discovery in Dorsetshire, in a stream not far from London, and we have just now, December 6th, found it also in Essex, living under conditions similar to those under which they were discovered in Dorsetshire.

Dr. Benham is about to publish a Monograph on British earthworms, and doubtless the new worm will be duly honoured with a figure and description in that work.

We must finish this short and imperfect sketch, expressing a hope that we may some day be able to contribute for publication something on worms more worthy of the Dorset Natural History and Antiquarian Field Club than these few hurried lines.

Broxted, Essex, December 7th, 1888.

ALLOLOBOPHORA.

LUMBRICUS.

F. O. P. C.

ALLURUS.

Transverse sections showing the disposition of the eight setæ in the

three genera.