THIED, OE VEEMICEEAN BEANCH. 143 



is sometimes identified with Amm. Liasicus in Germany, but that species has a 

 form more like Johnstoni, a larger keel, and entirely distinct sutures. 



A specimen from Aldingen, in the Museum of Stuttgardt, shows an entirely 

 smooth senile whorl, precisely similar in form to that described above in the 

 collection of the Museum of Comparative Zoology, though it is not half the size, 

 the diameter being 103 mm. Another from Vaihingen had a living chamber still 

 incomplete, though nearly one and a half volutions in length. On the latter 

 part of the eighth volution in this specimen the sides began to become flatter 

 and convergent, and on the ninth and tenth volutions the form was subtrigonal, 

 the channels absent, the pilse still prominent though obsolescing, and the keel 

 reduced to a raised line ; diameter, 163 mm. Another, of nearly the same size 

 as Hauer's figure of Amm. spiratissimum, agreed closely, the sutures also being 

 identical. The form of the whorl is, however, slightly more flattened laterally. 

 It belongs to the large variety of carusense, and is found, according to Hauer, 

 with Conybeari, rotiformis, and bisulcaius, in the " gelben kossener Schichten of 

 Enzesfeld." A specimen from Elwangen, labelled Amm. torus, in the Geo- 

 metricus zone, exhibits all the characteristics of the large specimen described 

 above. It has larger and stouter whorls and pite than the specimens described 

 from the Lower Bucklandi beds, though the sutures and other characteristics 

 are similar. A specimen of this variety from Aalen also occurs in Professor 

 Quenstedt's collection at Tubingen, with larger and more prominent pike than 

 usual. 



The young and old stages of this species at Semur and elsewhere are usually 

 identified either as torus, or toriilis, or Johnstoni, because of the resemblances of 

 the stages of development and senility in the different species of this series. 



Caloceras longidomum, Hyatt. 



Amm, longidomus, Quenst., Amm. Schwab. Jura, p. 50, pl.»vi. fig. 1, 2. 

 Amm. longidomus ceger, Quenst., Ibid., pi. vi. fig. 3. 



This species, as described and figured by Quenstedt, cannot be classified 

 with certainty. Not having seen specimens unquestionably referable to the 

 species, we cannot positively decide as to its true affinity. It is, according to 

 Quenstedt's description, a more immature or primitive form than spiratissimum, 

 since he alludes emphatically to the resemblances between the young and 

 Psiloceras. He also states that the young are closely allied to the young of 

 spiratissimum. This evidence seems to conflict, but the sutures, their backward 

 inclination, and the fact that the abdominal lobe, though longer than the supe- 

 rior laterals, is only slightly longer, the not very prominent and curved pilas of 

 Quenstedt's figure, the broad keel and slight channels, and the somewhat com- 

 pressed form of the older whorls, are all characteristics similar to those of caru- 

 sense. It may be a variety of carusense larger than the French, and becoming 

 senile more slowly. The curved pilaa are not like laqueum, and the cjdindrical 

 whorl and tendency of the pilne to cross the abdomen in the young also suggest 

 connection with carusense. 



