20 BRITISH FOSSILS. 



" this) antiqua, although only a coarse impression of it is left. The 

 " whole length of this individual, from the base of the arms to the 

 " apex of the phragmocone, is above 14 inches." 



At a previous page (777) Wagner states that a few hooks lie beside 

 the head of this specimen, and that the form of its body is exactly like 

 that of A, Ferussacii. " But what giv.es this specimen its greatest 

 " value is the circumstance that, in the posterior part of the mantle-sac, 

 " at its posterior as well as at its two lateral edges, a few delicate 

 " fragments of a brown, horny, irregularly fissured pen (Schulpe) are 

 " visible." 



In the second essay ("Ueber die SchalenlosenCephalopoden des oberen 

 Juragebirgs), Miinster says he is not certain what kind of mantle or 

 pen might have belonged to Acanthoteuthis speciosa, nor has he any 

 knowledge of the pen of A. Ferussacii, or of A. Lichtensteinii ; but 

 he proceeds to describe some new species, prefacing his account of them 

 with some general remarks, as follows : 



" The bodies of all the species known to me have a narrow elongated 

 form, which sometimes is elliptical, sometimes ovate, sometimes fusiform, 

 or even conical. Since, in a few specimens, impressions of booklets 

 are discoverable at the upper part of the body, which agree perfectly 

 with the three foregoing, and besides, coprolites not uncommonly occur 

 in the slates, which consist exclusively of the remains and undigested 

 parts of these naked cephalopods, namely, of the middle keel of the pen, 

 which is crushed into 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 ; I have not hesitated to 

 ascribe all these bodies and pens to the genus Acanthoteuthis, until 

 this view is upset by complete specimens," p. 57. 



Thus * Acanthoteuthis ' speciosa turns out to be one of the Belem- 

 nitidce, but the statements before us leave it doubtful whether it was 

 like Belemnoteuthis, devoid of an elongated guard, or whether it is 

 really a Bclemnites scmisulcatus with the guard broken off. 



With respect to " Acanthoteuthis" Ferussacii, of which only one speci- 

 men exists, Wagner is uncertain as to its distinction from the former 

 species, and believes it to be identical with A. Lichtensteinii ; and at any 

 rate, as the head and trunk have left only an impression, and not a 

 trace of any internal parts is to be seen (Wagner, I.e., p. 775), there is 

 no evidence to show that it, also, may not be a Belemnites, or a Belem- 

 noteuthis. 



Of the other Acanthotetithes enumerated in the second memoir, 

 Count Miinster does not profess to have found hooks associated with 

 A, angusta, A. lata, A. subovata, A. subconica, A. acuta, A. brevis, A. 

 intermedia, A. rhomboidalis, A. semistriata, and A. tricarinata, all of 

 which are referred to a different genus, Plesioteuthis, by Wagner ; while 

 Wagner, after examination of the same specimens, denies the existence 

 of hooks in A. Orbignyana and others, to which Munster ascribed 

 them. 



Thus, the existence of Acanthoteuthis as a genus apart from Belem- 

 nites, or Belemnoteuthis, becomes exceedingly doubtful. But it does not 

 follow from this that no other Mesozoic Cephalopoda were provided with 

 hooked arms, and indeed there is evidence that at least two genera, 

 Plesioteuthis (Wagner) and Celceno (Munster) were. In the first place 

 Count Miiuster afiirms, and Professor Wagner agrees with him, that 

 coprolites are not unfrequently found in the Solenhofen slates, "which 

 " consist exclusively of the remains of undigested parts of naked cephalo- 

 " pods, namely, of the middle keel of the pen, which is crushed into 



