1878.] FROM JAPAN AND BORNEO. 499 



kozoologie,' 1847, p. 44) for the reception of the curious shell 

 figured by Martyn under the name of Lituus brevis. 



It only differs from Myxostoma in having the inner lip of the 

 aperture sinuated above, and in the wing-like expansion of the outer 

 rim not leaning upon the penultimate whorl. The canaliculate suture, 

 I presume, is only a specific character. 



In all respects agreeing with this species are two others, Cyclo- 

 stoma planorbuJus, Lamarck, and Pterocyclos albersi, Pfr. The 

 former has had several localities quoted as its home, among which 

 are Senegal?, Philippine Islands, Bengal, Java, Borneo, Sumatra (in 

 Mus. Cuming), and Pulo Condore Island. Which of these is the 

 true habitat I cannot say with certainty, nor am I aware that it has 

 ever been definitely settled ; there is, however, some slight evi- 

 dence to show that the last locality is the correct one. We are also 

 in the same state of uncertainty respecting Pt. albersi. Pfeiffer 

 described the species not knowing its locality ; and Benson ('Annals 

 of Nat. Hist.' 1857, vol. xix. p. 208) is wrong in attributing a shell 

 found at Teria Ghat, Khasia hills, India, to this species ; for it was, 

 as shown by Hanley (' Conchologia Indica,' p. 56), only a variety 

 of Pt. parvus, Pearson. 



Here, then, is a small group of four species, all having a Pterocy- 

 cloid expansion of the outer rim of the lip, and an operculum of 

 precisely the same structure. Three of them have channelled sutures 

 to the whorls, are of a depressed orbicular form, and have the inner 

 lip sinuated at the termination of the sutural channel. The fourth 

 (brevis) and the type of Myxostoma lacks the channelled suture, 

 and has only the slightest trace of a sinus in the lip — both of which 

 characters, especially the former, I consider more specific than 

 generic. From Cyclophorus with its simple concentric thin horny 

 operculum and simple lip to the aperture, the different operculum 

 and expansion of the lip of Myxostoma warrant, at all events, a 

 subgenerie separation. 



There are two or three Burmese species ( Cyclophorus pinnulifer, 

 Benson, G. calyx, Benson, and C. hispidulus, Blanford) which will 

 also conveniently range under this genus. They are depressed sub- 

 discoid shells with a double rim to the aperture, the outer lip with 

 a small superior wing-like expansion, and the operculum thick, horny, 

 with the outer margins of the whorls lamellated. For this group 

 Blanford proposed the name Scabrina (Journ. Asiatic Soc. Bengal, 

 1863, p. 322). 



The museum is indebted to Mr. J. B. Sowerby for a single speci- 

 men of this interesting species. 



