BBITISH FOSSILS. 21 



u many short pieces, and of the booklets of the arms, which, sometimes 

 " large and sometimes small, lie scattered round the fragments of the 

 " pen, in great numbers." Wagner adds to this (l.c., p. 785) that the 

 fragments of the pen are part of the keel and of the lateral wings of 

 pens, appertaining, almost wholly, to animals in which the latter are 

 sword-shaped and thin, and for which Wagner proposes the generic 

 name Plesioteuthis. It would therefore appear that Plesioteuthis 

 had hooks, though Wagner's statement that he had never, either in 

 Minister's collection, or any other, found hooks associated with these 

 sword-shaped pens,* is, so far as negative evidence goes, somewhat 

 against that conclusion. 



In the next place, Professor Wagner (l.c., p. 783) describes an im- 

 pression of Celceno conica displaying hooks similar to those of " Acan- 

 thoteuthis Ferussacii" and, in addition, the remains of acetabula.f 



Upon the whole it becomes plain that the Acanthoteuthes of Munster, 

 so far as they are known only by hooks and impressions of soft parts, 

 may have been either Belemnites, or Belemnoteuthes, or Plesioteuthes, 

 or may have belonged to the genus Celceno ; and that, with the evi- 

 dence before us, it is impossible to say whether Acanthoteuthis speciosa 

 and Ferussacii belong to Belemnites, or to Belemnoteuthis. 



Under these circumstances, it appears to me that there is no good 

 ground for abandoning the name Belemnoteuthis, applied by Pearce to 

 one of the best known and most clearly definable of fossil Cephalopoda, 

 for Acanthoteuthis. Though it is quite possible that either A. spe- 

 ciosa or A. Ferussacii may be really a Belemnoteuthis, we have no 

 certain knowledge of the fact ; and even if such be the case, it would be 

 better to separate these forms as Belemnoteuthis, and to retain Acan- 

 thoteuthis for the Plesioteuthis of Wagner. 



The genera hitherto enumerated in the family of the Belemnitidce, 

 characterized among the Dibranchiate Cephalopoda by possessing a 

 straight, chambered, siphunculated, internal shell, or phragmocone, are 

 Belemnites, Belemnitella,\ Belemnoteuthis, Beloptera, and Conoteuthis. 

 To these Xiphoteuthis must now be added, and I think it very probable 

 that by-aud-by it will be found necessary to subdivide Belemnites, the 

 difference between the pro-ostraca of B. Bruguierianus and B. Puzo- 

 sianus being, probably, of generic importance. 



The extent of our knowledge of the structure of these different 

 genera is very unequal. Of Belemnoteuthis, the body and arms, hooks, 

 ink-bag, and internal shell are all known, few fossilized animals having 

 left more complete remains ; of Belemnites, the specimens described in 

 this paper have made known, for the first time, the form and proportions 

 of the body and the arms, the hooks, the ink-bag, one type of pro- 



* Out of coprolites, that is to say. 



t Wagner speaks of these as "hitherto never observed in fossil Cephalopoda" 

 (p. 783). but he has overlooked a paper " On the fossil Cephalopoda constituting the 

 " genus Belemnoteuthis," by Mr. J. C. Pearce, F.G.S., published in the " London 

 " Geological Journal," Xo. II., February 1847, in which the acetabula of Belemnoteu- 

 this are described and figured. (PI. XVI.) 



J See, however, -with respect to BelemniteUa and Actinocamcu-. the important 

 observations of Saemann, " Observations sur Belemnites quadratus, Defr." Bull, de la 

 Sociuto Gcologique de France, 1862. M. Saemann brings forward evidence to show 

 that these apparently distinct generic types arise merely from the defective calcifica- 

 tion of the upper part of the rostrum of a Belemnite. 



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