Mr. W. H. Benson on the genus Alycseus^ Gray. 181 



sato, exteriore reflexo, interiore crenulato quadriplicato aperturam 

 vix coarctante, labio simplici, tenui, marginibus callo crasso pro- 

 minente junctis. Umbilico profundo, margine rotuiidato. Oper- 

 culo ? 



Diam. major 4, minor 3|, axis 3 mill. 



Habitat in valle Rungun. 



The constriction of the last whorl is near the aperture, with- 

 out any intermediate ridge or swelling, in this respect show- 

 ing an affinity with Amphora and Urnula. In the crenulation 

 of the peristome it exhibits an analogy with sculptilis of the 

 normal group, in which the crenulations are twelve in num- 

 ber, with the origin of the sutural tube remote from the aper- 

 ture. 



The specimens examined are all weathered and bleached. It 

 is a singular circumstance, that each of the three natural sections 

 of Alyccms should have an analogical connexion through the 

 plicate peristomes of sculptilisj pledocheilus, and crenulatus. 

 The genus Pterocyclos, as above noted, has also its analogical 

 representative of the form in P. bilabiatus; and it is worthy of 

 remark that it claims affinity with Alycceus, as well as with 

 OpisthoporuSy through the aberrant P. hispidus, Pearson, which 

 exhibits a retroverted sutural siphon, although the structure of 

 the operculum, which is very similar to that of its siphonless 

 near relative, P. tenuilabiatus, Metcalfe, confirms its location 

 among the Pterocycli. 



AlyccEUS constriduSj B., var. minor. 



I find in the collection four specimens of a small variety of 

 this shell, bleached, but otherwise agreeing with the specimen 

 which I noticed in the 'Annals' for Oct. 1852, when recording 

 the additional character for the genus afforded by the presence 

 of the sutural tube. I can find no other feature to distinguish 

 it from the type than the more flatly expanded and distinctly 

 doubled peristome, in addition to the smaller size. As yet, only 

 a single specimen of the larger type is known ; it is in a fresh 

 state, but slightly mutilated, and the colour is paler than in my 

 specimen of the smaller type. The latter is deficient in the 

 distant ribs, but they are plainly visible on more than one of 

 Mr. Blanford's weathered examples. A fuller comparison of a 

 series of fresh specimens of the two forms will be required to 

 decide on their claim to separation. 



Alycaus sty lifer, B. 



Several specimens in the collection correspond in all parti- 

 culars with the description in the 'Annals' for March 1857, 

 founded on a single example. Unfortunately the shells are all 



