266 ^lessrs. Hancock & Attliey on an nndescn'beJ 



pores at the bases of the arms of Caryocrinus^ and in part, as 

 I shall show in another part of these notes, of the ambulacral 

 oriiices of the ti-ue Crinoids. 



With regard to the stiiictnre of the calyx of Peiitremttes, it 

 is generally supposed that there are only three series of plates 

 — the basal, radial, and interradial. !^ir. Lyon has advanced 

 the opinion that there are three small plates below those now 

 called the basals (Geol. Ky. vol. iii. p. 468, pi. 2. %. 1 c). 

 I have examined a number of specimens with reference to this 

 point, and I think he is right. There are three small penta- 

 gonal basals, the two upper sides of each of which are exca- 

 vated to receive the subradials, i.e. those at present designated 

 " the basals." They are in general anchylosed to the sub- 

 radials ; but in one of Mr. Lyon's specimens that I have seen 

 they are distinctly separate. 



[To 1)6 continued.] 



XXVIL — Xote on an undescribed Fossil Fish from the Xeics- 

 ham Coal-shale near XeiccastJe-upon-Tyne. By Albany 

 Hancock, F.L.S., and Thomas Atthey. 



For several years past we have been much puzzled with a 

 large ichthyic tooth that is not by any means uncommon at 

 Newsham. We could not make out to what fish to assign it. 

 Indeed there is but one, of sufficient size, found in the locality, 

 of which the teeth are not known, that was at all likely ; and 

 the remains of this were supposed to belong to Rhizodus ; and 

 as the teeth in question are perfectly devoid of cutting-edges, 

 they could not belong to it. We had doubts, however, as to 

 these remains really being those of that obscure fossil, and 

 thought that probably they would be found some day or other 

 associated with our unknown tooth — that it belonged, in fact, 

 to these supposed Bhizodus-hones. And such is apparently 

 the case. 



A jaw has just been obtained at Xewsham with one of these 

 large enigmatical teeth attached, and the smface-omament of 

 the bone is of the same character as that of the remains alluded 

 to. This jaw, which is a left mandible, is quite perfect in 

 front ; but the proximal extremity is broken away. The part 

 that remains is upwards of seven inches long, and an inch and 

 five-eighths wide ; the margins are nearly parallel ; the alveolar 

 border is pretty straight, but rises up a little in front, which is 

 rounded. About an inch behind the anterior exti-emity, a 

 large stout laniary tooth is placed on this elevated part ; it is 

 slightly recurved, but the apex is gone. What remains mea- 



