THIRD, OR VERMICERAN BRANCH. 153 



Caloceras Ortoni, Hyatt. 



Caloceras Orloni, Hyatt, Proc. Bost. Soc. Nat. Hist., XVII., p. 367. 

 Locality. — Tingo, near Chacapoyas, Northern Peru. 



The shell is fully preserved in the only specimen found. This form resembles 

 Gal. salinarium of the Northeastern Alps more than any other species. There are 

 the same closely crowded fold-like bent pilse without geniculse, similar narrow 

 channels with depressed lateral ridges and sunken keel, and similar gibbous form 

 of whorl, flattened abdomen, and discoidal aspect. The young were studied in 

 section. The earlier stages are excessively broad and smooth for three whorls. 

 Coarse tubercular folds appear on the latter part of the third or first quarter of the 

 fourth volution, near the abdomen. These gradually lengthen, but remain very 

 broad folds separated by wide depressions during the entire fourth whorl. There 

 are about twenty pilae on this whorl including the tubercles, thirty-five on the 

 fifth, and perhaps fifty-eight on the sixth. 



Occasionally a pilation is wanting, indicating the former presence of a more or 

 less constricted aperture, but these, though numerous, are not at regular intervals. 

 Occasionally pilations are doubled, but these are not shown in the figure. 



On the seventh whorl there are about eighty pilae, and on the latter part of 

 this volution they begin to lose their prominence, and on the latter part of the 

 eighth they suddenly degenerate into coarse crowded striations. These changes 

 are accompanied by a very slight elevation of the abdomen, broadening and 

 shallowing of the channels, while the keel appears to be more prominent. 



The young whorls are similar to those of Cal. Liasimm. The keel appears as 

 a low, broad ridge on the first quarter of the sixth volution, but the channels 

 were not present, in the section examined, until first quarter of seventh volution. 

 They are at this time very shallow and narrow, and the keel is also depressed and 

 not very broad, but on the eighth volution both these parts become more fully 

 developed. Effort was made by removing the shell to see the sutures, but not 

 with success. The auxiliary portions of the sutures are inclined posteriorly, but 

 otherwise nothing was satisfactorily ascertained. 



Cal. (Ariet. proaries var.) latecarinahim, "Wanner, 1 is the geographical equiv- 

 alent of the broad, depressed-whorled varieties of Cal. Liasicum of the Middle 

 European province. Wahner considers that Loki may be the nearest affine 

 to Gal. Liasicum, taking as his guide Reynes's figure of the latter. This means 

 only the compressed varieties of this species, which we have noted in the first 

 subseries. The extreme depressed whorls of latecarinatum are closely similar 

 to the next form of the subseries Gal. (Ariet.) salinarium, figured on Plate XVIIL, 

 and this is very likely, as supposed by Wahner, an old specimen of salinarhts, 

 though described by Giimbel as Amm. euceras. Cal. (Ariet.) centauroides, Wah., 2 

 exhibits very stout whorls in the young, and acquires the deep channels and 

 well developed keel at a late stage of growth, and these continue to be better 



1 Mojsis. etNeum., Beitr., V. pi. xvi. 2 Ibid., VI. pi. xxiv. 



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