Hyatt.] 370 [January 20, 



when fully two inches in diameter and a much thicker whorl. The 

 genus is dedicated to Leopold Von Buch in memory of the great 

 services rendered by him in the study of the fossil forms of the 

 Ammonoides. Buchiceras Harttii (Ceratitis Hartiii Hyatt in Hartt's 

 Geol. and Phys. Geog. of Brazil, Boston, 1870) is doubtless a mem- 

 ber of this group, though not closely allied to any of the species here 

 described, either in form or septa. 



Buchiceras bilobatum Hyatt. 



One well preserved specimen in light blue compact limestone well 

 filled with other fossils, was found at Cachiyacu, on the west side of 

 the river Huallaga in Northern Peru. This presents the condition 

 of the sutures at a young stage when the shell is about an inch in di- 

 ameter. Buchiceras syriacum Von Buch, with which it has been previ- 

 ously identified by myself and other authors, is very distinct, espec- 

 ially at this stage of growth. The short, numerous club-shaped cells 

 of B. syriacum each regularly divided by a median minor lobe, are 

 represented by two large cells with scalloped edges. These and the 

 superior lateral lobe occupy the entire breadth of the side. The ribs 

 and form resemble closely those of Buchiceras syriacum. 



Buchiceras serratum Hyatt, n. s. 



There are two interesting specimens of this from the same lime- 

 stone at Cachiyacu. The abdomen, however, instead of being acute 

 in the young, and becoming squared and blunter with age, continues 

 to retain its youthful sharpness, though the whorl grows much thicker 

 proportionally in the largest specimen, which is about three inches in 

 diameter. The septa of the young, when the shell is about an inch 

 in diameter, present very peculiar characteristics. The abdominal 

 lobe is very broad and short, containing a broad, squarely shaped ab- 

 dominal cell with perfectly smooth outline. The superior lateral cells 

 slope gradually up from this, beginning with what, at first sight, 

 ■appears to be an independent cell, which is really only the least prom- 

 inent branch of the superior lateral cell. The superior lateral lobes 

 are shallower but broaden out at the top, and are minutely serrated. 

 The inferior lateral cells are very broad, with plain sutures, the infe- 

 rior lateral lobes very much shallower and also minutely dentated. 

 Three auxiliary lobes are visible, mere nicks with broad flattened cells 

 between. The branches of the superior lateral cells become subdivi- 

 ded by the growth of a median minor lobe at the base of each, but 

 the remaining cells remain entire. The form of the superior lateral 

 cell, the depth of the superior lateral lobes and the shallowness of the 



