342 Mr. W. H. Benson on Tanystoma, Nematura, and Anaulus. 



XXIX. — Remarks on the Genera Tanystoma, Nematura, and 

 Anaulus. By W. H. Benson, Esq. 



Mr. H. Aiums having kindly brought to my notice the previous 

 employment of the term Tanystoma^ for a genus of Coleoptera, 

 and of Nematura for a genus of Birds, it appears advisable that 

 fresh names should be given to those testaceous groups. 



The term Tanystoma was assigned, in the February Number 

 of the ' Annals ^ for the present year, to a curious Anostomatous 

 form from Burmah. The designation Hypselostoma, having re- 

 ference to the uplifted position of the mouth of the shell, is now 

 substituted for the former appellation. 



Nematura was described in 1836, in the 5th volume of the 

 ' Journal of the Asiatic Society of Calcutta,' from the shell and 

 animal of a single species, N. Delta, which I had found at low 

 tide in the mud of the river Hooghly opposite to Calcutta. The 

 genus has since that time been increased by several species, from 

 other parts of the Eastern World, and some yet remain to be 

 described. The name has been adopted, in systematic and other 

 works, as referring to a genus of Testacea ; but Fischer having 

 iirst employed the term, in 1813, in another department of 

 zoology, I propose to designate the shell as Stenothyra, a title 

 expressive of the contracted structure of the aperture. 



Pfeiffer's description of Anaulus in the ' Proc. Zool. Soc.^ for 

 1855, p. 105, does not indicate the course of the canal or tube, 

 which terminates in the outer portion of the double peristome 

 in A. bombycinus, as well as in his new species A, Lorraini, from 

 Pulo Penang, described in a paper read to the Zoological Society 

 at a recent Meeting. In the latter species, the opening, at first 

 sight, might be supposed to be altogether outside of the peri- 

 stome, but on a closer inspection is found to be embraced by a 

 portion of it. In both species the canal or tube is sutural and 

 internal, and can be traced externally along the last whorl, at 

 the extremity of which it ascends more rapidly in A. Lorraini 

 than in the original species. 



In a specimen of A. Lorraini I was unsuccessful in an attempt 

 to penetrate the canal with a bristle ; but in one of ^. bombycinus 

 I have succeeded in passing a hair, through the canal, into the 

 concavity of the spire. Mr. H. Adams informs me that Mega- 

 lomastoma Chrysallis, Pfr., is also an Anaulus, with a similar su- 

 tural tube, a fact which was ascertained from an accidental per- 

 foration at some distance from the aperture. He further stated 

 that the anterior opening was partly concealed by the reflected 

 portion of the peristome. 



* Motschoulsky. 



