﻿10 NORWOOD AND PKATTEN ON PRODUCTI. 



This species is dedicated to our friend, Prof. Henry D. Rogers, as a slight testimony 

 of our high appreciation of his labors in American geology. 



/Section III. 

 PEODUCTI PROBOSCIDEI. 



Productus clavus, nob. — PI. I., fig. 4, a, b, c. 



This very singular shell is the only one of the class we have met with, and it is in 

 so imperfect a state of preservation that for some time we hesitated about including 

 it in the present notice. Like its European congeners, however, it is so rare, and so 

 remarkable in form, that we have concluded to figure it, and give such a description 

 as the mutilated specimen before us will admit of, in the hope of being able to furnish 

 a more complete one when we shall be so fortunate as to secure more perfect speci- 

 mens. 



This species is small, longer than broad, the dorsal valve is divided into two very 

 distinctly marked parts, distinguished especially by the direction of the bands and 

 ribs. The visceral portion is slightly arched, and covered with well defined trans- 

 verse bands, separated by somewhat deep furrows, the furrows being ornamented by 

 delicate strise, having the same direction as the bands. The bands are about twenty 

 in number, and appear to reach, all of them, up to the cardinal border on both sides. 

 They are narrower towards the beak, and increase in width, although not regularly, 

 as they approach the front, some of them being more prominent than others. The 

 beak is small ; pointed ; shows no evidence of a median sinus ; and appears to pass 

 little, if any, beyond the cardinal border. 



The prolongment is cylindrical, and slightly contracted at its junction with the 

 visceral portion ; straight, and in the direction of the axis of the shell. It is covered 

 with broad, regular ribs, numbering about twenty in the space of ten millimetres. 

 The ribs of the prolongment can be traced on to the last fold of the visceral part, 

 giving it a reticulated appearance. Whether the prolongment was closed all round, 

 as in the P. proboscidews, or open on the ventral side, as in the P. genuinus, cannot 

 be decided from the imperfect specimen before us. 



Dimensions.-^- Length of the visceral part, 11 millimetres \ breadth the same. 

 Diameter of the prolongment, 7 millimetres ; length of the part preserved equal to 

 that of the visceral portion. 



Comparisons and Differences. -^-It differs from the P. proboscideus of Mr. de Verneuil 

 with which alone it can be confounded, in the longitudinal ribs not extending over 

 the visceral portion, and in the prolongment not showing the numerous and well- 

 marked transverse folds of that species. The longitudinal ribs of the proboscideus 

 are also much finer, numbering about fifty in the space of ten millimetres at the 

 anterior border of the visceral part. Our species shows no trace of a sinus. 



