312 AMERICAN JODKJ<(AL 



ON THE LINGUAL DENTITION OF POMPHOLYX BFFUSA. 



BY THOMAS BLAND AND W. G. BINNEY. 



In the Annals of the New York Ljceum of Natural History, 

 vol. ix, p. 290, we described and figured the lingual dentition of 

 Pompholyx effusa. We now give a more detailed illustration on 

 plate 18. 



The individuals examined were among the specimens from 

 which the species was, in the first instance, described. They 

 were received by us from the Smithsonian Institution, with Dr. 

 Lea's original label. There can, therefore, be no doubt about 

 their identity. 



The figures were obtained by photography, the negatives being 

 taken directly from the microscope by our friend Mr. Sam. Powel. 

 This process secures absolute accuracy up to the point of trans- 

 ferring the outlines upon the lithographic stone. Here, of 

 course, we are dependent upon the fidelity of the artist. 



To the description of the lingual already published, which we 

 copy below, we have added more details regarding the recurved 

 apex of the laterals. 



Lingual membrane broad, with 22.1.22 teeth. Central teeth 

 long, narrow, widening and knobby at the base ; apex recurved, 

 and produced into an obtuse beak. Laterals nine on each 

 side of the central line, in a straight, transverse row, wide, quad- 

 rate, apex recurved, prolonged beyond the base of the tooth in 

 a more or less broad blunt beak, which is normally furnished at 

 either side with a short, sharp denticle. Marginals about thirteen 

 on each side of the median line, in oblique, transverse rows, not 

 attached to a plate, simple and not recurved ; the first eight from 

 the extreme lateral edge of the membrane long, narrow, arm- 

 shaped, terminating in a wrist-like contraction and hand-like 

 expansion, strongly digitate. The remaining marginals gradu- 

 ally changing into the shape of the laterals, but still not merging 

 into them, the line of demarcation being strongly marked. 



There is great variation in the beak-like projection of the re- 

 curved apex of the laterals, and still more in the digitation of 

 the marginals. 



