ball: mollusca and brachiopoda. 339 



way up the cone of the shell aud distally project prominently beyond the periphery 

 of the base. The characteristics of the anatomy are described by Dr. Pelseneer, 

 in a paper following the description above cited, from which it appears that the 

 animal is without eyes, possesses two very short tentacles, aud on the right side 

 from the base of the right tentacle extends a rather long, pointed verge, grooved 

 on the outer ventral side. The mouth contains a single unpaired jaw, aud a long 

 radula with the formula 1 • 4 • • 4 • 1, the uncinal tooth being plate-like, aud the 

 third lateral larger than any of the others and furnished with a strong cusp. The 

 rhachidian tooth is absent. The middle of the surface of the foot is produced or 

 protruded, taking the form of the excavation upon which the animal rests. There 

 are no gills either pallial or ctenidial, and Dr. Pelseneer believes that respiration is 

 performed, as in Lepeta, by the surface of the mantle. The nervous system recalls 

 that of the Docoglossate Limpets, there are two otocysts, each containing a single 

 otolith. 



The animal appears, unlike most of the true Limpets, to be hermaphrodite, pos- 

 sesses a heart with a single ventricle, two renal organs, aud a large hepatic gland. 

 Dr. Pelseneer concludes that the family belongs in the Docoglossa, to which so 

 many of the anatomical characters point. 



Desiring to have the most careful examination made of the Pacific species, 

 specimens were sent to Dr. Johaun Thiele, of the Royal Zoological Museum at 

 Berlin, well known from his anatomical researches on Mollusca.^ It will be noted 

 that tlie B.pacificum is considerably larger than the Atlantic form, giving a better 

 opportunity to the anatomist for studying the minor details. 



Bathysciadium paciflcum Dall, n. sp. 



Plate 9, figures 1, 3, 7. 



Shell small, circular, conical, in every case witli tlie apex eroded but evidently 

 central or slightly in advance of the centre ; color whitish, with a smooth, polished, 

 concentrically faintly striated surface, a rather thick chalky layer being originally 

 situated on a porcellanous inner coat ; on the exterior the periostracum has a rather 

 remarkable disposition and character ; there are about twenty radial lines upon the 

 surface on which the periostracum is developed in long fringe-like hairs which are 

 not a continuous series but coustitute a line of successive whorls extending some- 

 what beyond the margin of the shell; these are divided usually into groups of five 

 radii, the lateral radii have the whorls of hairs extremely long and abundant, es- 

 pecially beyond the margin, where, when the animal raises itself to admit water 

 and food between the shell and its situs, these fringes cloak tlie sides so uo sedi- 

 ment can enter between the shell and its pedestal ; the anterior and posterior 

 groups of radii have the whorls sliort, not extending niucii beyond the margin, 

 thus by ciliary action an anterior incurrent and jiosterior excurrent llow is doubt- 



1 Dr. Thiele's results will appear separately iu the Bulletin Mus. Comp. Zoology. 



