FIFTH, OR AGASSICERAN BRANCH. 213 



second quarter of the fifth whorl in the St. Thibault specimen, the channel ridges 

 are still raised lines marking the angular junctions of the sides and smooth 

 channel areas. On the last part of the same whorl in the third specimen just 

 mentioned, and in fact on the second quarter, even this angularity has almost 

 wholly disappeared, the channels being obsolete, the keel therefore additionally 

 prominent. • The involution of the last part of the fifth whorl covers three fourths 

 of the sides of the preceding whorl, exclusive of the channel area and the keel, 

 which would somewhat increase this amount. 



Oppel refers this species to the young of Guibalianus, our Oxyn. Greenoughi, in 

 which, however, he was probably mistaken. The specimens in our possession, 

 show that this species has not been correctly quoted as coming from any other 

 localities than Cote d'Or, the basin of the Rhone, and perhaps Hierlatz. 



Sutures of the first specimen described above on the third quarter of the 

 fourth whorl had lobes differing from one third to one half, and saddles about 

 one third ; and the third specimen on the first quarter of the fifth whorl had 

 lobes differing one third and saddles a trifle less. The outlines of the suture are 

 similar to those of Coroniceras and Asteroceras. Three saddles are to be seen 

 upon the side, the inferior laterals being deeper than the superior laterals, as in 

 other species, but the first auxiliaries are unusually large, nearly as deep as the 

 inferior laterals, and very broad. The abdominal lobe, as stated, is from one half 

 to one third longer than the superior laterals, and the superior lateral saddles 

 about one third shorter than the inferior laterals. There is therefore no ground 

 for the reference of this species to the genus Amaltheus, as has been supposed by 

 some authors. According to Oppel this species is found in the Tuberculatus bed, 

 and though Oppel probably never saw a true Collenoti, this statement is approxi- 

 mately correct. Dumortier's specimens of Collenoti (Cluniacensis) were found in 

 his Planicosta bed immediately above the Oxynotus bed, and all of his beds 

 above the Bucklandi and Davidsoni (Striaries) beds are equivalents of the Birchii 

 or Tuberculatus zone at Semur. D'Orbigny's originals were reported as coming 

 from the Gnjplwa arcuta beds, but this was evidently considered to be doubtful 

 by Oppel, even before Dumortier found his specimens. 



The extraordinary series figured and described by Wright from the Oxynotus 

 bed, under the name of Slattcri, are widely distinct. The figures of the shell and 

 sutures we have quoted above are certainly taken from a species which is very 

 closely allied with the true Collenoti. It is assuredly an Arietian, with affinities 

 allying it to obtusum, and comes nearer to Collenoti than any other species in 

 respect to involution, smoothness, form of whorl, and abdomen. The other mem- 

 bers of Slatteri as figured are probably diseased specimens of obtusum. 



The keel of this species was examined very carefully to determine whether 

 it was solid or hollow, and it was found to be solid. 



A dwarf form of Ast. (Ariel) slellare is figured by Geyer in his " Lias. Geph. 

 d. Hierlatz b. Hallstadt," and his Ast. ( Oxyn.) Collenoti is certainly very similar to, 

 if not identical with, the French form of that name. Asteroceras ( Ariet.) stellaforme, 

 Wah., Mojsis. et Neum., Beitr , VI., Plate XXVI., seems to be a species of this 



