ME. G. BEOOK 0"N- A NEW GENUS OF COLLEMBOLA. 541 



Its aspect aud general tint recall the half-forgotten D. stra- 

 mineus of Grmelin, a shell fairly defined, from its combined figure 

 and description, by Schroter. It does not display, however, the 

 purple stain on the hinder slope, and widely diff"ers in outline. 

 The grooves are feebly decussated by minute radiating lines at 

 the broader end (which is oblique, rounded below) . 



Darwin's figure of Lepas crassa conveys the impression of the 

 general shape (except the posterior outline) of this very rare 

 shell, of which I have never seen but one example. 



DoNAX IMPAE, n. sp. (Plate XII. fig. 4.) 



Testa parva, maxime insequilateralis, valde elongata, compresso- 

 cylindracea, antice rotundato-acuminata, postice brevissima et 

 abrupte truncata, Candida, poKta, omuino Isevis, nisi ad aream 

 posticam planam aut concavam, ubi concentrice est sulcata. 

 Margo dorsalis anticus vix declivis ; margo ventralis haud crenu- 

 latus. 



Long. 0'7, lat. 0"2 poll. Hab. Beloochistan {Blanford). 



The nearest approach to this remarkably elongated shell is 

 D. Owenii ; but the present is still more inequilateral. I possess 

 only a single valve ; but as it is in fine preservation, and as in the 

 section Maclicdrodonax both valves are alike, I venture to describe 

 it ; the colour, however, may vary. 



In the plate I have added a few illustrations of species of 

 Leptomya &c. hitherto unfigured. 



DESCRIPTION OF PLATE XII. 



Fig. 1. Donax Mesodesmoides, u. sp.. i Fig. 7. i. S;pecifa5j7is, slightly enlarged. 



nat. size. ' Fig. 8. L. cochlearis, Hinds, nat. size, 



Fig. 2. D. Listen, n. sp., nat. size. | from unfigured type in the British 



Fig. 3. jD. flavidus, n. sp., enlarged. [ Museum. 



Fig. 4. B. iinpar, n. sp., enlarged. j Figs. 9 to 12. Teredo uticulus. G-mel., 



Fig. 5. Leptomya gravida, Hanley, valves and pallets, the latter en- 



nat. size. I larged. 



Fig. 6. L. psittacus, Hanley, nat. size. | 



On a new Genus of CoUembola (Sinella) allied to Degeeria, 

 Mcolet. By G-eoege Beook, F.L.S. 

 [Eead June 15, 1882.] 

 The genus Degeeria was founded by Nicolet, in 1842, for the re- 

 ception of those species of the old Linnean genus Podura which 

 have the antennae shorter than the body, consisting of four sub- 

 equal segments and a minute basal ring, abdomen tapering, with 

 the fourth abdominal segment longer than the three preceding 

 taken together. The specimens here described were collected 



