MUSEUM OF COMPARATIVE ZOOLOGY. 77 



Yucatan Strait, 640 fms. 



The peculiarities of the apical tube are quite as great in this species as in 

 the preceding when compared with typical Punctiirella ,- but I cannot consider 

 them as of even sectional importance. It is hardly necessary to add that the 

 species does not resemble any of the ordinary forms, nor has it, so far as I am 

 able to determine at present, been anywhere previously described. 



Emarginula RoUandi Fischer. 

 Sigsbee, off Havana, 450 fms. Station 21, 287 fms. 



Emarginula sp. indet. 

 Yucatan Strait, 640 fras. 



FAM. PLEUROTOMARIID^ Ball. 



> Pleurotomaricc Swainson, Mai., pp. 213, 223, 363 ; as subfamily of Trochidce ; 1840. 

 >< Plcurotomariidce Chenu, Man., I. p. 236, 1862. In suborder Proboscidifcra 



near Scalariidce. 



> Plcurotomariidce Bronn, Keferstein Thierreichs, Mai., III. 1037, 1866. 



> Pleurotomariidcc Stoliczka, Pal. Indica, Gasterop., p. 380, 1868. 



? Plcurotomariidce Gill, Fam. of Moll., p. 11, No. 132, 1871. (Limits not stated.) 



Shell trochoid in form, internally pearly, the last whorl perforated or fis- 

 sured, for the escape of eggs or fecal matters, in the direction of the coil of the 

 whorl. 



Operculum horny, subspiral or multispiral. 



BranchicE two, nearly symmetrical, one on each side of the slit in the mantle 

 corresponding to the fissure or perforations of the shell. 



Animal with papillose edge to the mantle and lateral fringes ; without elon- 

 gated cirri as in the Trochids ; with no frontal veil, or fissuring of the foot. 

 Muzzle simple, without a proboscis, eyes on pedicels exterior to the bases of the 

 simple tentacles. Jaws small, weak. 



Dentition. Rachidian tooth small, lanceolate or broad bayonet-shaped, lat- 

 erals rather simple, numerous, similar, diminishing in size outwardly, followed 

 by a large number of long slender uncini, many of which are denticulate near 

 their tips and also furnished with a little tuft of bristles or a brushlike bunch of 

 fibres attached to the side of each uncinus behind the denticulations, the tips 

 of the fibres projecting beyond the end of the uncinus.* 



Distribution. Fossil in Lower and Upper Bala groups. Upper Cambrian of 

 Sedgewick, and thence to recent times; two species living in the Antilles, one 

 of unknown habitat, probably Japanese. 



* More minute details will follow hereafter in an account of the two species 

 obtained. 



