144 G. Nevill — New or little-known [No. 3, 



living animal covers its shell with a thick coating of mud, arranged in a 

 quasi-symmetrical manner, as I have also seen in species of Succinea 

 Pterocyclus, &c. ; the operculum externally is distinctly concave. 

 Diam. 6£, alt. 4| mil.— Cebu. 

 Diam. 5f , alt. 3 mil. — Guimaras. 



Pfeiffer records typical G. jpusillus, ex coll. Cuming, as diam. 11, 

 alt. 6 mil. 



Hab. — Cebu (type var.) and Guimaras. This small Oyclotus was 

 found tolerably abundantly by Surgeon-Major Hungerford, living on the 

 ground, in company with species of Pupina and Acmella, &c. 



Genus Cyathopoma, Blanford. 



Colonel Beddome has already pointed out, and I believe it is now 

 generally accepted as correct, that Jerdonia and JSLycliopoma, Blanford, 

 can only be retained as sections or subgenera of Cyathopoma. Hitherto 

 the genus has been supposed to have a very limited range, but this is not 

 so in fact, as it extends as far as the Pacific Archipelago where the species 

 are known under the name of Diadema, Pease ( = Garettia, in Catal. Paetel 

 and Mus. Godef.) ; the type species of Pease's Diadema (Pterocyclos ?) 

 parvus, Pease, 1865, from the Hervey Islands, is, as regards its shell, a true 

 Cyathopoma, being wonderfully close to Gya. filocinctum, only rather 

 smaller : its operculum is correctly described by Pease as follows : — > 

 " O. subcartilageum, elevatim spiraliter lamellatum, intus concavum, basi 

 late reflexwn ;" the very concave shape gives it a striking resemblance 

 to that of many species of Pterocyclus. Reference to the original descrip- 

 tion of the operculum of Cyathopoma will at once show that no separation 

 can be effected on this character only : " O. truncate conoideum, concentri- 

 cum, multispirum, e duahus laminis compositum ; interna membranacea, 

 externa testae ea per concav a ; anfractuum marginibus externis in lamellam 

 testaceam, versus medium incurvatam,interdum pulchre sculptam, elevatis" 

 I consider therefore that Diadema must rank as a subgenus of 

 Cyathopoma, distinguished by its Pterocyclus — like operculum, and that 

 it is of approximately equal value with Jerdonia. The following is 

 Blanford's original description of the operculum of Jerdonia: — " O. con- 

 centricum, arctispirum, sulco marginali circumdatum, duplex; interne 

 onembranaceum, exteme testaceum et ex anfr. vittaeformibus compositum, 

 quo que proximi interioris marginem externum tegente^ 



It is very remarkable that at the Hervey Islands another small shell 

 occurs with all the characters of the shell of Jerdonia and closely resem- 

 bling, indeed, the tj^pe species J. trochlea ; this is the Gyclostoma biangulatum 

 of Pease, P. Z. S. 1864, referred to Gyclophorus (Ostodes) in the Donum 

 Hismarcldanum and still more correctly, I consider, to Cyclomorpha of 



