292 Geoloyical Society. 



exhibited photograijhic slides o£ examples in tlie British-Museum 

 collection showing these various characters, and noted the abrupt 

 termination of the chambered cone on the lower part of the pro- 

 ostracum, of which the dorsal surface may ha\e been partly or 

 almost completely covered by a thin forward extension of the 

 guard. To illustrate Avhat was known of the complete body of 

 the animal as found associated with the guard, he then showed 

 photographic slides of two of the examples figured by Huxley 

 in his ' Memoir on the Structure of the Belemnitidaj ' published in 

 1864. Each of these exhibited the guaixl associated with portions 

 of the i^ro-ostracum, the ink-bag, and the booklets of the anus. 

 The form of the booklets with their thickened bases was discussed, 

 this feature in a great measure justifying the attribution to the 

 belemnite of certain cephalopod remains (found practically at 

 about the same geological horizon) that included uncinated arms 

 associated Avith an ink-bag, and frequently also with nacreous 

 portions of (presumably) the pro-ostracum. 



Of the remains of uncinated armed cephalopods from the Lias, 

 each exhibiting the same form of booklets as those figured by 

 Huxley, he said that the British-Museum collection contained 

 seventeen examples, all from the neighbourhood of Lyme Regis and 

 of Charmouth, in Dorset. Each specimen exhibits a nmnber of 

 imcinated arms associated usually with an ink-bag, sometimes also 

 with nacreous matter, and in two instances also with the guard or 

 rostrum. These two examples were those to which he had ab'eady 

 referred as having been figm-ed by Huxley, and unfortunately 

 the arms are not well preserved in either of these specimens ; in 

 one (jB. hruguierianus, from the Lower Lias near Charmouth) 

 there are only a few scattered booklets, while the arms of the 

 other {B. elongatus, from the Lower Lias of Charmouth) are 

 represented only b}' a confused mass of booklets. Of the other 

 fifteen examples, in one there are a few solitary booklets ; in 

 another the number of the arms is very indistinct ; in two the 

 remains of onh' two arms are preserved ; in one there are traces 

 of three arms ; in two there are indications of three, or possibly 

 four, arms ; and in one there is a confused mass of possibly four 

 arms ; and in one there are the remains of fovir, or possibly of five, 

 arms. In each of the remaining six specimens six arms can 

 be more or less clearly made out, wliile there is not a single 

 example in which more than six uncinated arms are displayed. 



Of the six examples that exhibit six uncinated arms four are 

 stated to be from the Lias of Lyme Kegis ; one is from the Lias of 

 Charmouth ; and one was obtained from the Lower Liassic shales 

 between Charmouth and Lyme Regis. From a consideration of 

 these specimens, the speaker concluded that the cephalopod repre- 

 sented by these mieinated arms is the animal known as the 

 belemnite, and that the six uncinated arms were arranged in three 

 pairs of unequal length, of which the longest pair was lateral, the 

 medium-sized pa ir pro b a b 1 y dorsal, and the shortest pair probably 



