S. V. Wood— The Long Meadend Bed. 65 



plain that these two spines, though not belonging to the same fish, 

 form in other respects a pair, right and left. 



A third specimen repi-esents the distal portion of a spine broken 

 off after the closure of the sulcus, but fortunately with the point 

 entire. It is 2* inches in length, and 1-f- inch in circumference 

 proximally, whence it tapers to a pretty sharp point. The unsym- 

 metrically trigonal form of the transverse section, the nature of the 

 striation of the surface, and the appearance, internallj^ of the tissue 

 of which it is composed, show clearly that this fragment is the 

 terminal portion of a spine of the same species as the two already 

 noticed, and it may also be observed that, as regards the direction 

 in which it is unsymmetrical, it belongs to the same category as 

 No. 2. But the point of special importance in this specimen is that, 

 extending from the apex for a distance of --^ inch along the posterior 

 aspect, are two rows of small recurved denticles, each row being 

 placed slightly within the rounded margin sepai-ating the posterior 

 from the corresponding lateral surface. The denticles on the broader 

 side of the spine are nearly all perfect, and are nine in number, those 

 on the narrow side are only eight, and are mostly broken off, though 

 still indicated by the fractured bases, — I ma}'' add that they were per- 

 fect before the specimen was removed from its matrix. The distance 

 between the denticles in each row increases from about iV inch at 

 the apex to \ between the last two, but the increase is not regular, 

 so that the denticles of the two series are not always opposite. The 

 surface of the denticles is smooth, nevertheless there is no appearance 

 of a covering of enamel. 



This new spine is of great interest from the analogies with 

 Gyracanthus which it presents in many important points of its con- 

 figuration. As in Gyracanthus, we have here a spine which is not 

 bilaterally symmetrical, the posterior area being turned awry, which 

 occurs in pairs, and which accordingly may safely be looked upon 

 as a lateral aj^pendage. One of the specimens presents appearances 

 at the apex which I am inclined to interpret as " wearing," though, 

 if so, the wearing is on the posterior aspect. But though the wear- 

 ing in Gyracanthus spines is usually anterior, I have certainly 

 seen it also on the posterior aspect in specimens from Borough Lee. 

 Here, however, the resemblances cease, as the present spine is pro- 

 portionally short and stout, is devoid of distinctive sculpture, and its 

 mode of denticulation is very different. 



From the want of shining enamel or ganoine on the surface, which 

 want is certainly not due to abrasion or erosion in any specimen I 

 have seen, I propose to call the present new genus and species of 

 Selachian spine Aganacanthus striatulus. 



III. — The Long Mead-End Bed. Further Eemaeks. 

 By S. V. Wood, F.G.S. 



BY the kindness of Dr. Henry Woodward, Keeper of the Geological 

 Department of the British Museum, I have been furnished with 

 a list of shells which have the locality " Mead End " attached to 

 them in the Edwards Collection in that Museum. 



DECADE III. VOL. I. NO. II. 6 



