132 Br. R. H. Traquair on the 



the apex of the plate just mentioned. Here we have two sets 

 of interspinous bones articulated end to end with each other 

 and with the neural spines, which latter are truncated and 

 not pointed. In a very good specimen in the British Mu- 

 seum I count about fifteen ossicles in the proximal set and 

 twelve in the distal, though probably the numbers were equal 

 in the perfect state, and in both sets they have the same form, 

 namely they are slender, elongated, and expanded at both 

 extremities. It is evident from the last-mentioned circum- 

 stance that the ossicles of the second row are not dermal fin- 

 rays, but belong to the same category as those of the first ; 

 two rows of interspinous bones being, in fact, of constant, 

 occurrence in the primitive Ganoids. 



Beyond the dorsal fin the neural spines become very short 

 as well as less oblique in their direction. 



On the haemal aspect of the vertebral axis no such elon- 

 gated apophyses occur anteriorly, as depicted in the restora- 

 tions of Agassiz and Pander. Immediately behind the lateral 

 plates of the cuirass we find small, nearly circular, haemal 

 pieces without spines, then spines are added which, gradually 

 lengthening, become longest in the region opposite the dorsal 

 fin, whence they again diminish towards the extremity of the 

 tail. It is this peculiar lengthening of the hsemapophyses 

 under the dorsal, a fact also noticed by M'Coy, which has 

 evidently given rise to the old idea of the presence of an anal 

 fin. 



In all specimens of Coccosteus where the internal skeleton 

 is well preserved there is found a pair of peculiar slender bones 

 (a;), each of which is pointed at both ends and bent below 

 the middle at an obtuse angle in somewhat L-shaped fashion, 

 the long limb pointing upwards towards the vertebral axis, 

 the short one forwards. These bones were noticed by Pander 

 (6, p. 73), who, though extremely doubtful as to their nature, 

 supposed that they " vielleicht den Extremitiiten als Stutzen 

 der weichen Flossen angehorten." Their position is certainly 

 suggestive of their having had something to do with pelvic 

 limbs — more I cannot say. 



Mr. A. Smith Woodward has pointed out to me that in 

 several specimens in the British Museum a small oval or 

 somewhat rhombic bony plate (y) is seen lying in a position 

 posterior to the last-mentioned bones. I have not observed 

 it in any other specimens than those ; but its presence in a 

 similar position in more than one example would seem to 

 indicate that it was a scute placed in the ventral mesial line. 



Were 'pectoral members 'present ? — I have now examined 

 with the utmost care a very great number of specimens of 



