ANIMAL TO ITS SHELL IN SOME FOSSIL CEPHALOPODA. 87 



from tl)e greater part of the body -chamber, and the latter can fortunately be removed 

 from the rest of the specimen. The whorl is carinate, subquadrangular in transverse 

 section, its sides mnch flattened and nearly jiarallel to each other ; at the base of the 

 body-chamber it is 13'5 mm. high and 10 mm. thick. On the left side of the specimen 

 (PI. 18. fig. 9), near the base of the body-chamber a feebly-impressed (on the internal 

 cast) line arises from the suture of the sliell [i. e. the inner edge of the whorl) 4'5 mm. iu 

 front of the last septum ; it extends outward and backward almost as far as the septum, 

 nearly reaching the same at the inner side of the second (or inferior) lateral lobe ; it then 

 turns outward, as if to pass over the adjoining saddle, and soon disappears. When the 

 body-chamber is detached (PL 18. fig. 10) this incised line is seen to be continued on to 

 the impressed zone, being also indicated by a difference of colour, the portion posterior 

 to the boundary being much lighter than the rest of this surface. Prom the edge of the 

 Avhorl this boundary passes a little backward in an /"-shaped curve nearly to the central 

 line of the im2:)ressed area, when, turning abruptly backward, it passes nearly parallel 

 to the median line of this area as far as the small saddle adjoining the antisiphonal lobe. 

 The corresjjonding line on the other side of the impressed area iias the same form, so far 

 as it can be traced, but the edge of the whorl on this side is somewhat imperfect. A 

 line of coloiu" apj)ears to indicate that the median space between the two boundaries was 

 bridged over anteriorly. Tlie form of the muscular attachment just described on the 

 impressed area of the outer whorl is confirmed by its appearance on the inner surface 

 of the dorsal portion of the test of the body-chamber, which remains attached to the 

 l)receding whoii. 



The muscular scar on the right side of the body-chamber is not preserved, the inner 

 portion of the base of the body-chamber having been broken off. 



On the middle of the left lateral area there is a linguiform space, 8 mm. long and 

 ■1 mm. broad, enclosed by a very faint line, open behind and convex anteriorly (PI. 18. 

 fig. 9). Its lateral boundaries are nearly parallel to the inner and outer margins of 

 the whorl respectively, the inner being l-'o mm. distant from the inner margin, and the 

 oiiter at the same distance from the periphery of the whorl. The inner boundary passes 

 just into the inferior lateral lobe along its outer side, and the outer boundary just passes 

 into the superior lateral lobe along its inner side. There is a similar linguiform area on 

 the middle of the right side of the body-chamber, 95 mm. long and 6 mm. wide, oj)en 

 behind, and Avith a convex anterior boundary. Its inner boundary passes just into the 

 inferior lateral lobe at its outer side, whilst the outer boundary passes just into the 

 superior lateral lobe along its outer boundary, and not its inner, as on the opposite side 

 of the body-chamber. Hence the linguiform area on this side is somewhat broader than 

 that on the left side, the inner boundary being at about the same distance from the inner 

 edge of the whorl, while the outer is nearei the periphery than on the opposite side. 



Only in this one specimen have these linguiform areas been observed ; but, as they are 

 so distinctly displayed on both sides of the fossil, it is just possible that they are 

 connected with the attachment of the animal to its shell. This example seems to support 

 the figure given by Trautschold. 



SECOND SF.KIES. — ZOOLOGY, VOL. VII. 13 



