PTEROPODA. 



271 



Fig. 244. (^onularia or- 

 itata. Devonian. 



The genus Conularia is one of the most extraordinary of the 

 extinct genera of the Pteropods, if only for the enormous size 

 attained by many examples. The shape 

 of the shell is very like that of some 

 living Pteropods, but specimens occa- 

 sionally reach the length of nearly a foot, 

 with a breadth of more than an inch. 

 The shell in Conularia (fig. 244) is 

 straight, tapering towards one end, and 

 having a sub-quadrate or rhomboidal 

 aperture at the other. The form of the 

 shell is generally distinctly four-sided, 

 the sides being finely striated with trans- 

 verse lines. The shell is generally of 

 extreme tenuity j but the internal cavity 

 is sometimes restricted by concentric 

 lamellae, and the apex maybe partitioned 

 off. M. Barrande enumerates eighty-three 

 species of Conularia, most of which are 

 Palaeozoic, commencing in the lowest Silurian deposits. The 

 genus, however, extends into the Mesozoic Rocks, the last 

 species, so far as at present known, appearing in the Lias. 



Lastly, the genus Tentaculites comprises a number of singular 

 Palaeozoic fossils, the true position of which cannot be said 

 to be absolutely free from doubt. Most authorities now place 

 Tentaculites, with apparently good reason, in the Pteropoda ; 

 but others would still refer this genus to 

 the Tubicolar Annelides. It must be ad- 

 mitted, also, that in some respects Ten- 

 taculites approximates pretty closely to the 

 Annelidous genera Conchicolites and Cor- 

 nulites. Upon the whole, however, the 

 mode of occurrence of Tentaculites and 

 its undoubted free habit of existence leave 

 little doubt as to its true place being 

 amongst the Pteropods. The shell of 

 Tentaculites (fig. 245) has the form of a 

 straight conical tube, tapering towards one Fig. 245. 



' . j j i j j ornatus. Upper Silurian. 



extremity to a pointed closed apex, and Europe and North America, 

 expanding towards the other to a circular 

 aperture. The walls of the shell are thin, and are surrounded 

 "with numerous thickened rings or annulations, sometimes with 

 intermediate striae, over a whole or part of the length of the tube. 

 The size of Tentaculites varies much in different cases, being 

 sometimes less than a couple of lines in length, and sometimes 



