THIRD, OE VEEMICEEAN BEANCH. 137 



Caloceras Johnstoni, Hyatt. 



Amm. Johnstoni, Sow., Min. Conch., p. 464, pi. ccecxlix. 

 Amm. torus, D'Orb., Pal. Francaise Ceph., p. 212, pi. liii. 

 Amm. psilonotus plkatus, Quenst., Aram. Schwab. Jura, pi. i. fig. 12, 13. 

 Amm. Johnstoni, Quenst., Ibid., pi. i. fig. 20. 

 JEgoc. Johnstoni, Wright, Lias Amm., pi. xix. fig. 3, 4. 

 JEgoc. Belcheri, Wright, Ibid., pi. six. fig, 1, 2 (not pi. xv. fig. 7-9). 

 JEgoc. Johnstoni, Neum., Unterst. Lias, Abhandl. geol. Reichsans. Wien, VII. pi. iii. fig. 2. 

 JEgoc. torus, Neum., Ibid., pi. iii. fig. 3. 



JEgoc. Johnstoni, Wah., Unt. Lias, Mojsis. et Neum., Beitr., IV. pi. xvi. fig. 6-9. 

 Localities. — Wiesloch near Heidelberg, Bristol, Cheltenham. 



This form differs from planorhe in the outline of the whorl, which is much 

 narrower, more rotund and gibbous laterally, and in the greater prominence of 

 the pilaB. 



A specimen in the Museum of Stuttgardt measuring 120 mm., labelled tortilis, 

 Niirtingen, has a living chamber still incomplete, though nearly one volution in 

 length. Abdomen is slightly more elevated than in typical adult torus and the 

 sides more inclined, as is usual in old age of this species. Otherwise the form 

 and pilse, especially in the umbilicus, are the same. 



Sutures of adult are similar, as far as seen, to those of Psiloceras, and in old 

 age the lobes and saddles decrease in size, becoming simpler in outline. Quen- 

 stedt's specimen, figured in" Ammoniten des Schwabischen Jura," Plate I. Fig. 20, 

 is 110 mm. in diameter and shows the effects of senility in the compressed whorl. 

 His Figure 13 shows the living chamber to have been at least one volution in 

 length. The typical forms of this series are found in the Northeastern Alps, but 

 the distribution is general, as has been already noted by Neumayr. 



In the collection of the Sorbonne at Paris there is one specimen from Beaure- 

 gard precisely similar to that figured by D'Orbigny, except that the whorls are 

 much larger and stouter. In the collection at Munich there are specimens from 

 Pfonsjoch, Kander in Bresgau, and Lyme Begis, exhibiting the typical form of 

 Johnstoni until they reach the diameter of 145 mm. 



Var. Beauregardiense. 

 Amm. Beauregardiensis , Collenot. 



This form from Beauregard in the collection at Semur is 185 mm. in diameter, 

 and has whorls increasing more rapidly in size than in the typical Johnstoni, but 

 otherwise does not differ from that species. 



Caloceras tortile, Hyatt. 



Plate I. Fig. 12-14. Summ. PI. XI. Fig. 14. 



Amm. tortilis, D'Orb., Terr. Jurass. Ceph., p. 201, pi. xlix. 

 Amm. raricostalus. Dunk., Paleontogr., I. pi. xiii. fig. 17. 

 JEgoceras intermedium, Wright, Lias Amm., pi. xv. fig. 5, 6 (not fig. 3, 4). 



Amm. laqueus (pars), Quenst., Amm. Schwab. Jura, p 19, pi. i. fig. 15, 16 (not fig. 14, nor p. 18, fig. 4). 

 Localities. — Semur, Rinteln, Quedlinburg. 



This species is very generally misinterpreted by German and English paleon- 

 tologists. The young have exactly the same broad, gibbous whorl as the young 



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