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 Cyclophoride*. 
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 Alyce from the same locality. 
20. Mrcatomastoma, Guilding. 
Three species from India and Burma have been assigned to 
this genus, viz. :— 
M. funiculatum, Bens. Darjiling. 
M. pauperculum, Sow. Bhotan. 
M. sectilabre, Gould. Tenasserim. 
A fourth very closely allied species is found in Borneo. 
I have very little doubt that M. pauwperculum 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 Cataulus. 
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- 
__ * T have not been able to compare the lingual ribbons of these various 
forms, although I obtained several of them. 
