New species of the genera Pterocyclos and Cyclostoma. 105 



proper arrangement of the Solanacea and the genera more im- 

 mediately allied to them, and it certainly affords cause for regret 

 that at a period of excellent opportunity, with such abundant 

 materials, with every facility at command, and with a consider- 

 able amount of assistance from others, so imperfect a digest of 

 the family should have appeared in the highest standard work of 

 our time, the ' Prodromus ' of M. DeCandoUe. 



IX. — Descriptions of species belonging to the genera Pterocyclos 

 and Cyclostoma, fi-om Ceylon and West Australia. By W. H. 

 Benson, Esq. 



1 . Pterocyclos Cingalensis, nobis, n. s. 



Testa late umbilicata, orbiculato-depressa, solidula, radiato-striata, 

 albida, superne strigis subundatis, medio fascia castanea picta ; 

 spira planiuscula, apice vix prominulo, sutura profunda impressa ; 

 anfractibus 5, convexis, ultimo lente descendente, superne alato, 

 breviter soluto ; ala prominentiam elongatam angustam ascen- 

 dentem formante, postice carina obtusa desinente ; apertura ob- 

 liqua, subcirculari ; peristomate duplice, interno porrecto, superne 

 profunde incise, externo incrassato, superne dilatato, leviter de- 

 flexo ; umbilico profundiusculo. Operculo (teste E. L. Layard) 

 pyramidali, 



Diam. major 19^, minor 16, alt. 6 mill. 



Hab. ad vicum montanum Monahagalla, Insulse Ceylon. Teste Dom. 

 Edgar Leopold Layard. 



Distinguished from Pt. rupestris by the length and narrowness 

 of the alar prominence, which ascends slightly on the penulti- 

 mate whorl, and runs parallel with it, instead of spreading semi- 

 circularly as in that shell. From Pt. Albersi it differs not only 

 in size, but in the absence of the incurvated beak which is such 

 a prominent feature in that species. The umbilicus, equally 

 broad with that of Pt. rupestris, is somewhat deeper in pro- 

 portion. 



This very interesting addition to a genus, which, though still 

 limited in number, receives yearly additions from our Eastern 

 possessions, was found by Mr. Layard in the central mountain 

 region of the island, the fauna of which he is so successfully in- 

 vestigating. A monograph of the genus Pterocyclos, including 

 all the species hitherto published, will be found in Dr. Pfeiffer's 

 'Monographia Pneumonopomorum' recently issued, including, in 

 a compact volume, excellent descriptions of all the known Cyclo- 

 stomacea and Helicinacea, with references to the figures given in 

 the ' Conchylien Cabinet,' Sowerby's ' Thesaurus,' &c. 



