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ON A DIBRANCHIATE CEPHALOPOD (PLESIOTEUTHIS) FROM 

 THE LITHOGRAPHIC STONE (LOWER KDIMERIDGIAN) OF 

 EICHSTADT, BAVARIA. 



By G. C. Cbick, F.G.S., F.Z.S., of the British [Museum (Natural 



History). 



(Published by permission of the Trustees of the British Museum.) 



Read 14th May, 1915. 



PLATE IX. 



Although the genus Plesioteuthis, instituted by Dr. A. Waguer 

 (6, p. 785) iu 1860, is perhaps the best-known dibranchiate Cephalopod 

 (see Zittel, 7, p. 519) from the Lithographic Stone of Bavaria, 

 particularly the species P. prisca, an example of this genus in the 

 British Museum collection from Eichstadt, Bavaria, is so excellently 

 preserved, and displays certain cliaracters which have not been 

 previously recorded in any described example of the genus, that it 

 seems to merit description. It is the subject of the present note. 



The fossil is displayed on the surface of a slab and exhibits a dorsal 

 aspect of the specimen. It is almost symmetrically arranged and 

 exhibits tlie body with its fins, the head, and the arms. A stellate 

 mass of calcite in the head appears to rejDresent the cavity of the 

 buccal mass. 



The Body is elongated, broadest at about two-fifths of its length 

 from the anterior margin {e), which is indicated by a narrow shallow 

 transverse groove, rather more than one-fourtli of its length. At the 

 anterior margin the body appears to have been about 65 mm. wide ; 

 thence it tapers very gradually to about 56 mm. at a distance of 

 about 60 mm. from the anterior margin; it then expands rather 

 rapidly, attaining its greatest width of 74 mm. at about 110 mm. 

 from the anterior margin ; from the point of its greatest width 

 it tapers evenly towards the posterior end for about another 

 95 mm. After gradually expanding for about 20 mm. it again 

 tapers evenly to the end of the body. Here there are four 

 obscure, almost symmetrically disposed spinous processes which seem 

 to have belonged to the animal. Two are at the extreme end 

 of the animal, their bases 8 mm. apart, feebly inclined outwards, 

 and roughly about 13 mm. long. The others are situated at the 

 posterior end of the line of junction of each fin with the body, and are 

 also of about the same length (13mm.). Tlie writer has not seen similar 

 processes in any of the other examples of this genus in the British 

 Museum Collection. Judging from the impression of a portion of the 

 mantle displayed on each side of the body, the surface of the mantle 

 appears to have been finely granular. So far as the present writer 

 is aware, the presence oifins in this genus has not yet been recorded. 

 The specimen under consideration exhibits them very clearly. They 



