2 Woodward — On Actinoceras. 



Tlie following are the proportions of the Woolhopc specimen : — 



Extreme length of siphuncle composed of 9 beads, 4^ inches : transverse diameter 

 of largest bead of same, 9 lines ; vertical thickness of same, 7 lines ; transverse diameter 

 of smallrst bead, 6 lines ; vertical thickness of same, 4 lines ; greatest diameter of 

 shell, 2 inches; least diameter of shell, 1 inch 4 lines; interspace between one septum 

 and another in largest chamber, 6 lines ; in smallest, 3 lines. 

 Neither the apex or body-chamber of the shell being present, 

 we can only surmise its length. A section of Actinoceras giganteum(?) 

 from Derbyshire, i^reserved in the British Museum, measures 2 

 feet in greatest length and 3J inches in greatest breadth, and exhibits 

 thirtj^-eight body-chambers. An Orthoceras from Ireland, in same 

 collection, measures 2ft. 10^ inches in length and 16in. in circum- 

 ference. Many have been discovered even far larger than these. 



To this group, undoubtedly, belong the most gigantic forms 

 of the straight Nautilidce. 



The interest attaching to this most ancient group of chambered 

 shells is such, that I have gladly availed myself of Dr. Bull's kind 

 proposal to notice it in the pages of this Journal, accompanying the 

 notice with his excellent figure. I have not only carefully examined 

 the specimen myself, but have been favoured with the opinion of 

 Professor Morris thereon, and I am confirmed in the conclusion that 

 the Woolhope specimen is specifically distinct from any other 

 heretofore described. I have therefore (at the suggestion of Dr. 

 Bull) named it Actinoceras baccatum (in reference to the beautiful 

 bead-like structure of the siphuncle). 



The characteristic fossils obtained from the Little Hojoe quarries 

 in the Woolhope Limestone from whence A. baccatum was derived 

 are : Trilobites — lUcenus Barriensis, Homalonotus delphinocephalus, 

 and Pliacops caudatus. Mollusks — Orthoceras annulatum, Strophomena 

 depressa, S. eufjlyplia, S. pecten, Bhynchonella Wilsoni, and B. 

 Stricklandl, Cirrus — sp. ; and also Cornulitcs serpidarius and PtijcJio- 

 phjllum patellatum. 



The Little Hope or Scutterdine quarries (which are quite beneath 

 the Wenlock shale) are intersected by the Grcological Survey, section 

 No. 2 on sheet 13, and their precise position is laid down on the 

 Ordnance Map No. xliii., N.W. 



It is to be hoped that the Woolhope Naturalists' Field-club, 

 which numbers some excellent geologists among its members, will 

 detect further specimens of this interesting fossil, and that we may 

 be able, at a future day, to add a more full description to the 

 present very brief notice. 



STKPHEN AUSTIN, PRINTER, HERTFORD. 



