72 MR. G. C. CRICK OX THE MUSCULAR ATTACHMENT OF THE 



In his lai'ge works on the Triassic Cephalopoda, Dr. E. von Mojsisovics * has figured 

 several species of Ammouoids bearing on the internal cast of their body-chamber a groove 

 or grooves (extending in some examples from the umbilicus on one side, over the 

 peripliery, to tbe umbilicus on the other side), vrhicli he considered to be the impression 

 of the homologue of tiie muscular attachment of the recent Nautilus. 



Dr. O. Jaekel t, in 1889, figured a Ceratite from the Trias of Riidersdorf, near Berlin, 

 bearing a groove precisely similar to those figured by Dr. E. vou Mojsisovics, and 

 although he douljted this indicating the position of the homologue of the annukis 

 and of the shell-muscle in the recent Nautilus, he was unable to give any explanation 

 of its nature. After an examination of Oppel's original specimen, this author says the 

 line which Oppel figured and which has been regarded as indicating the position of the 

 anterior boundary of the anuulus and of the shell-muscle can scarcely be folloAved with 

 certainty, and he is inclined to doubt tiie correctness of the interpretation. 



In his ' Vorlaufige Mittheilung liber die Organisation der Ammoniteu ' +, Dr. Stein- 

 mann evidently does not agree with Dr. Waagen's interpretation of Oppel's specimens 

 (although he seems to make no special reference to them), a fact which is clearly brought 

 out in the ' Elemente der Palaontologie ' (1890) by himself and Doderlein, where (p. 351, 

 fig. 402) one of Oppel's figures (Pal. Mittheil. pi. Ixix. fig. 2) is reproduced, and tbe 

 curved line on the body-clianiber completed in the manner suggested by Waagen, but in 

 the explanation of the figure this line is thus described : " (?) vordere Greuze des 

 Haftbandes." 



At the meeting of the Geological Society of London which was held on March 25th, 

 1891, a communication was read from Mr. S. S. Buckman, entitled " Notes on Nautili 

 and Ammonites." Only an abstract of the paper was published §. Nautili and 

 Ammonites were exhibited in illustration of the paper, and, according to the abstract, 

 " Two specimens exhibited show long spatulate depressions more or less parallel to the 

 periphery for about half the length of the body-chamber. It was suggested that these 

 impressions indicated the position of the shell-muscles." 



So far, then, as I have been able to ascertain, no satisfactory examples exhibiting the 

 form and position of the musctdar attachment of the Ammonoid animal to its shell have 

 yet been figured and described either to confirm or to contradict the explanation whicli 

 AVaageu gave of Oppel's figures. 



The Ammonite animal may have been, and prol)ably a\ as, attached to its shell at the 

 edge of the last septum, as in the living Nautilus, but from my own observations it is 



* Abhaudl. d. k.-k. geol. Eeichsanst. Wieii, Bd. vi. Theil i. Heft i. (1873) pi. xvi. f. 3 {Phi/lloceras occidfum) ; 

 pi. xix. f. 1 (Pinucoceras transiens) ; pi. xix. ff. '2, 3, 4 & pi. xx. ff . 8 &: 9 {Pmacoceras Jiumile) ; pi. xx. ff. 2, 3, 5, & 

 7 (Pivxicoceras insectum) ; [il. xxii. ff. 7, 8 {Pi nacoceras mi/ophorum) ; ibid. Bd. vi. Hiilf'te ii. (1893) pi. cxxxiv. f. 1 

 {Choristocei'fis amiiwnh'ifornu); ihUl. Bd. x. (1882) pi. liii. f. 2 (Mec/aj}hi/lKtes sandalinus); pi. liii. f. ;5 {Mega- 

 phyllites oholus). 



t " Ueber eineu Ceratiteu aus dem Schaumkalk vou lliider.sdorf uud iiber gewisse als Haftring godeutete Eindriicke 

 bei Cephalopoden," Ncues Jahrb. 18S9, ii. p. 19, pl.i. 



+ Berichtc der naturforsehendcu Gesellschaft zu Freiburg, Bd. iv. Heft 3, jip. 31-47 (1889). 



§ Abstr. Proc. Geol. Soc. Loudou, Session 1890-91, p. 105 (Quart. Journ. Geol. Soc. vol. xlvii.). 



