the Cyclostomacea of Eastern Asia. 461 



the general form of the shell resembles Raphaulus. There is no 

 trace of a sutural tube, or of any modification of it. The oper- 

 culum is very peculiar, and unlike that of any other genus 

 amongst the Cyclophoridse*. 



A second species of this genus, very closely allied to H. gravida, 

 was obtained from the Laos Mountains, Cambodia, by M.Mouhot. 

 I am indebted to Mr. Hugh Cuming for specimens both of this 

 species and of the Alycai from the same locality. 



20. Megalomastoma, Guilding. 



Three species from India and Burma have been assigned to 

 this genus, viz. : — 



M. funiculatum, Bens. Darjiling. 



M. pauper culum, Sow. Bhotan. 



M. sectilabre, Gould. Tenasserim. 



A fourth very closely allied species is found in Borneo. 



I have very little doubt that M, pauperculum is merely a 

 variety of M. funiculatum. The latter species is common at 

 Darjiling, at 6000 to 7000 feet elevation. Above this elevation 

 a variety occurs in which the basal keel is less pronounced, the 

 shell somewhat thicker, and the colour of the epidermis oliva- 

 ceous ; and this I believe to be the form to which the name of 

 pauperculum was given. There is a complete passage between 

 the two varieties, the smaller of which formerly abounded on the 

 top of Sinchul, a mountain near Darjiling, between 8000 and 

 9000 feet high. 



M. funiculatum is peculiarly interesting, as showing in a rudi- 

 mentary form the basal keel which is typical of the Ceylonese 

 genus Cataulv^. 



Dr. Gould has suggested for the Asiatic species of Megalo- 

 mastoma the generic appellation of Coptocheilus, stating that, 

 with the exception of M. Antillarum, all the West-Indian species 

 differ greatly in form from the East Indian. This is true ; but 

 the exception vitiates the distinction. I have very little doubt 

 indeed that Dr. Gould's surmise of the distinctness of the 

 two types will prove to be correct, and that the oriental and 

 occidental species must be separated from each other ; but I do 

 not think that they have as yet been satisfactorily shown to have 

 generic distinctions. The animals of the Eastern forms are allied 

 to Pupina and Cyclophorus, having subulate contractile tentacles 

 of moderate length, with the eyes at the side of their bases, a 

 moderate proboscis, and a rather long undivided foot. The 

 lingual ribbon has not been examined. It is desirable to ascer- 



* I have not been able to compare the lingual ribbons of these various 

 forms, although I obtained several of them. 



