FIRST, OR PSILOCERAN BRANCH. 123 



Despl. d. Champ., locality Blumenstein am Thimer See. One of the specimens 

 from Filder shows the exact aspect and markings of Psil. planorbe, but has the 

 form of longipontinum. Though it is somewhat difficult to judge from a figure, 

 nevertheless, ^Eg. Clausi, Neumayr, very closely resembles Psil. longipontinum, 

 and we have considered it to be a variety of this species with somewhat stouter 

 whorls than the normal form. It is also a large aged specimen, and according to 

 Neumayr came from Wiirtemburg. 



Quenstedt referred this species, in his " Ammoniten des Schwabischen Jura," 

 to Cal. laqueum. His comparisons were evidently made with the old whorl of 

 laqueum, and, as this has no keel, and is smooth or with obsolescent pila?, it is of 

 course very like the adult stages of Psil. longipontinum. Nevertheless, both the 

 young and adult stages ot laqueum are easily distinguished from the same stages 

 of longipontinum. Quenstedt's figure shows the length of the living chamber to 

 have exceeded one volution. 



Tate and Blake's citation of this species from the Angulatus bed J is likely to 

 mislead. Their species is, as figured, a diseased Caloceras, or poorly drawn 

 species of Schlotheimia with pike crossing the abdomen, but certainly not, as 

 named by them, longipontinus. 



Species of the second subseries figured by Neumayr in the work quoted 

 above are as follows. Psil. cryptogonium, Plate VI., is discoidal. Psil. majus and 

 Gemense, Plate V., are slightly more involute shells. Warmer, in Volume IV. of 

 the work above quoted, figures Psil. sublaqueum, Plates XV., XVI., Psil. crebri- 

 cinctum, Plates XVI., XVI1L, Psil. pachydiscus and polyphyllum, Plate XVII., all 

 discoidal shells. This subseries and the preceding agree closely with the western 

 European forms except in the involute species. Wahner also figures, in Vol- 

 ume III. of the same work, Psil. Berchta and aphanoptychum, Plate XXIII., 

 which are discoidal, and Psil. pleuronotum, Plate XXV., calcimontanum, Plate 

 XXIV., and KummerJcarense, Plates XXIV., XXV, which are more involute and 

 compressed. 2 



Third Subseries. 

 Psiloceras Hagenowi, Wahner. 



Amm. Hagenowi, Ddnk., Paleontogr., I. pi. xiii. fig. 22, pi. xvii. fig. 2. 



Amm. Hagenowi' Terq. et Piet., Lias Inf. de l'Est de la France, Mem. Soc. Geol., VIII. pi. i. fig. 3, 4. 



Amm. Hagenowi, Quenst., Amm. Schwab. Jura, pi. i. fig. 18. 



Psil. Hagenowi, Wahner, Unt. Lias, Mojsis. et Neum., Beitr., IV. p. 196. 



The form of this shell approximates to that of Psil. planorbe, var. leve, but the 

 sutures are more widely distinct, and degenerate in outline. In Terquem and 

 Piette's figure they resemble quite closely the sutures of Popanoceras Kingianum 

 and antiquum, Goniatitinae of the Dyas. The lobes of that figured by Quenstedt 

 are not so coarsely dentate, and approximate more closely to the sutures of Psil. 



1 Yorkshire Lias, p. 273, pi. v. fig. 4. 



2 On Summary PI. si., outline figures have been given of the principal forms, aphanoptychum, fig. 11, 

 and Knmmerkarense, fig. 12. 



