BOTHRIOLEPIS MAC ROC 1 EPH ALA. 129 



of the undermost flat surface is well seen, while the outlines of the anterior and 

 posterior ventro-lateral and median ventral plates are clearly traceable. The 

 outer surface of the plates being lost, the sculpture is, of course, also invisible. 

 Both pectoral appendages are exhibited, and the finely denticulated or serrated 

 outer edge of the proximal segment is well seen in the appendage of the left side 

 (British Museum, P. 196). 



In Fig. 6 we have also the under surface of the animal, and its contour looks 

 broader on account of some amount of special pressure and flattening to which the 

 specimen has been subjected. In this example the denticulation of the outer 

 margin of the proximal part of the arm is seen to be proportionally just as strong 

 as in B. hydrophila (British Museum, 36442). 



The specimen in the British Museum (P. 195), from which fig. 9, pi. iii, in 

 Egerton's description is taken, but which is not reproduced here, shows a sharp 

 impression of the outer surfaces of the anterior ventro-lateral plates, and of a 

 portion of the left pectoral appendage, which impression is minutely tuberculated, 

 showing that the original sculpture of the plates themselves must have been of a 

 finely pitted character, resembling that of B. hydrophila. 



Remarks. — Originally described as a Pterichthys, this small Asterolepid was 

 transferred by myself to Bothriolepis, and its resemblance to B. hydrophila is so 

 great that it is designated by Dr. Smith Woodward in his 'Catalogue' as "a 

 variety or species, so far as known, merely differing from the typical B. hydrophila 

 in its much smaller size." However, the head, as indicated by Sir Philip Egerton's 

 specific name " macrocephaln '," seems to be proportionately larger than in the Dura 

 Den form, and so it may rest as a distinct species in the meanwhile. 



Sir Philip Egerton, in his original paper on this form, appealed to appearances 

 presented by the specimens he examined, and which are now all in the British 

 Museum, in support of his view, that the pectoral appendages of " Pterichthys " 

 were borne on a pair of " thoracic " plates separated by suture from the anterior 

 ventrolaterals. The fact is that, the bony matter of these plates being pretty much 

 scaled off, the impression of the internal transverse ridge, which passes across the 

 anterior ventro-lateral plate, a little behind the front, comes into view, which 

 impression on superficial examination is misleadingly suggestive of an actual 

 division. The non-existence of the so-called thoracic plates was amply proved by 

 myself for the Asterolepidas in general in 1888. 



Geological Position and Locality. — The only knowm specimens have been found 

 in the yellow sandstone (Upper Old Red) of Farlow, in Shropshire. 



