1875.] 367 [Hyatt. 



Gramm. striatulitm, but wants the forward curvature or inflexion of 

 the central part of the ribs which is so characteristic of all the radi- 

 ans group. If it were not for the keel it would be almost identical 

 with the finer ribbed varieties of JEgoceras angulation. The smooth- 

 ness and form of the young, the linear character, number, and pecu- 

 liar bend of the ribs, the abrupt geniculse, and arnioc eras-like 

 keel and narrow abdomen appear to demand a place for it in the 

 same genus with the preceding, and perhaps it might be considered 

 a variety of the Arnioceras ceras with smoother young than that first 

 described. 



Loc, Ipishguaniina. 



Arnioceras miserabilis ? Hyatt. 



Still another specimen obtained from the same block as No. 2 of 

 Arnioc. ceras, has smooth discoidal young and a form which, with 

 the exception of the keel, has the aspect of Amm. miserabilis of 

 Quensted. It is entirely smooth, very discoidal, and evidently pos- 

 sesses a very narrow, short whorl. 



Ipishguaniina is at an elevation of 11,000 feet above the sea level 

 according to Prof. Orton the highest point in Northern Peru. The 

 Ammonites are associated with a species of Lamellibranch which was 

 so badly preserved that Mr. Richard Rathbun, assistant in the 

 Museum of the Society of Natural History, was unable after close 

 study to identify the species or even determine the genus, his report 

 however is appended below. 1 



Caloeeras Ortoni Hyatt, (n. s.) 



This species is very similar in external characteristics to (he Amm. 

 sirouatus of Quenstedt; it differs from it principally in the greater 

 proportional breadth of the abdomen, the deep channels and well 

 developed keel. The living chamber is considerably over one whorl 



J Avicula (Gervilia?) sp? 



The two small impressions of Lamellibranchs from Ipishguaniina are moulds of 

 the left valve of the same specimen, one of the exterior, the other of the interior. 

 They indicate a form belonging to Aoicula, or perhaps Gervilia; their imperfect 

 preservation rendering the identification doubtful. To whichever of the above 

 genera they belong, they might represent any portion of the secondary age, since 

 both genera are common throughout that age in Europe. 



The shell is quite oblique, with its greatest length from the beaks nearly 12 mm. 

 and the diameter at right angles to this length a little greater than C mm. The an- 

 terior ear, if such existed, is entirely broken away ; the posterior is small and does 

 not extend very far backward, but it is imperfect. The impression of the hinge is 

 very obscure, and no indication is given of either the cartilage pits or the teeth. 

 The surface is marked with indistinct concentric lines of growth. R. R. 



