1875.] 371 [Hyatt. 



inferior and auxiliary lobes and cells remind one of the young of 

 Buchiceras bilobatum previously described, and indicate a direct gen- 

 etic connection. The sides round evenly from the umbilicus out- 

 wards, broken up by slight fold-like ribs with a median forward bend, 

 which splits into several hardly distinguishable folds having an ab- 

 dominal forward bend. The abdomen of the cast is obtusely angular, 

 owing to the depressed gibbosity of the sides. Associated with this 

 species in the same block of limestone were several fragmentary 

 fossils of various kinds which were examined by Mr. Richard 

 Rathbun, and his report upon them is given in a note. 1 



Appendix. 

 Peruvian Ammonites of the Hartt Collection. 



Buchiceras syriaciforme Hyatt. 



Several fine specimens from one inch to three inches in diameter, 

 confirm the observations made in the preceding pages. The largest 

 specimen is particularly interesting. The abdominal lobe, which at 

 younger stages is a little longer than the superior laterals, is here a 

 trifle shorter. The superior and inferior laterals are both visible on 

 the side, narrow and long, with triple branches unequally divided. 

 The superior and inferior lateral cells are much deeper and narrower 

 proportionally than in the young, with coarsely scalloped bottoms. 

 The same young specimens compare quite closely in sutural 

 characteristics with the typical B. sjfriacum from Lebanon. They 

 still differ, however, in the number of lobes and cells visible 

 on the sides, there being but three cells and two lobes as in the 

 adults. They differ even more widely from the young of Buchiceras 



1 The small fragment of hard grayish limestone from Cachiyacu, near Huallaga 

 River, Peru, with Buchiceras serratum, contains a great many other mollusks, but 

 on account of the exceeding hardness of the rock it is difficult to break the speci- 

 mens out in a condition suitable for their identification. They are all small and 

 belong mostly to common cretaceous genera. Among the Lamellibranchs is a 

 6mooth form of Avicula or Gervilia, not, however, exposing the hinge characters. 

 It resembles much in shape Gervilia enigma D'Orb., from the Turonien of France, 

 but is of much smaller size. There is also a medium-sized form of Leda, having 

 a nearly smooth surface, and another small shell quite abundant in the fragment 

 of rock, which is probably referable to Corbula. The hinge of this latter form is 

 not exposed. There are many casts of very small Gasteropods which seem to rep- 

 resent two species and two genera; one is a Turritella. Besides the mollusks just 

 mentioned there is a fragment of the scale of a teleostean fish, in a rather poor 

 state of preservation. R. R. 



