ACTINOCERAS. 33 



evidently bounded by true walls, must be regarded as an organic deposition after 

 the manner of those figured in some species of Orthoceras by Barrande. 



Hence it appears that whatever the species may be, it probably belongs to the 

 genus Orthoceras. 



2. Genus — Actinocbbas, Bronii, 1837. 



1. AcTiNOCBRAs? (Huronia) Crickii, n. sp. Plate IV, figs. 9? 10 — 12. 



Descrij)tion. — Shell rather large, straight, tapering rather rapidly at the rate 

 of about 1 : 6. Section elliptic, having the siphuncle situated excentrically, rather 

 in front of the centre along the longer diameter, and considerably distant from 

 the centre along the shorter diameter. Chambers narrow, very slightly oblique, 

 and about one-sixth of the width of the shell in height. Septa shallow, convex, 

 somewhat steeper in front, and having a wide, very shallow bay or sinus on the side 

 farthest from the siphuncle. Siphuncle very large, about two-fifths the width of the 

 shell; consisting of a series of subturbinate or vasiform rosettes, rather wider than 

 high, which sometimes appear thickened by organic (?) deposits ; and containing in 

 its centre a slight free subcylindrical endosiphon. Endosiphon suddenly expanding 

 just below the top of each rosette into about four radiating horizontal tubuli, 

 which branch into minor tubuli near their extremities, are supported by ridges 

 below, and are more or less joined to each other by their lateral expansions. 

 Septa meeting the siphuncle only a little below its widest part, and enfolding its 

 lower portion .[? Surface (on the cast) showing a long longitudinal carina and signs 

 of rather distant alternating threads or strias, fig. 9.] 



Size. — A specimen of twenty chambers is 80 mm. long by 25 mm. wide ; 

 another, of about eleven chambers, is 55 mm. long by 27 mm. wide. 



Localities. — Of external casts, probably belonging to this species, are two 

 specimens from Top Orchard, three from Pilton Vicarage Well, and one from 

 Premington in the Barnstaple Athenseum ; one from Baggy in the Museum of 

 Practical Geology; two from Pilton in the Porter Collection; and two from 

 Barnstaple and one from the south-west of Sloly in the Woodwardian Museum. 

 Of natural sections showing the siphuncle there is one " from Yeotomes " in the 

 the Barnstaple Athenasum; one from Croyde and one from Barnstaple in the 

 Woodwardian Museum; and one from the Marwood Beds in the British Museum. 



BemarJcs. — Most of the exterior specimens are very poor, and some are very 

 doubtful, and could hardly be identified specifically by themselves ; but from the 

 dimensions of their chambers and other points they appear most probably to 



B 



