16 



PROF. E. EAT LANKESTEE ON LEPIDOSIEEN AND PEOTOPTERUS. 



Table B. — Measurements of specimens o/" Protopterus annectens, Owen. 



The facts indicated by these two sets of measurements (excluding any close following 

 of the figures derived from the stufi'ed specimens of Protopterus) are, firstly, that the 

 proportional value of the measurements diff'ers greatly in difl'erent specimens ; and 

 secondly, that if we take a fair well-grown specimen of Protopterus on the one hand 

 and of Lepidosiren on the other, the former from 40-50 centimeters, and the latter 

 60-70 centimeters in length, they contrast most strongly in the following points — 

 namely, that in Protopterus the whole animal is about ^\ times as long as its head, 

 whereas in Lepidosiren the whole animal is about 10 times as long as its head. Next, 

 that whereas in Protopterus the inter-membral length is about 2^ times the length of 

 the head, it is about 5 times the length of the head in Lepidosiren ; and, lastly, that 

 whereas in Protopterus it is about once and a half the length of the head from the 

 pectoral to the commencement of the dorsal fin, it takes as much as three head-lengths 

 to cover the same line in Lepidosiren. The post-pelvic ratio of length is nearly the 

 same in the two genera. 



These external diiferences are, of course, accompanied by corresponding numerical 

 differences in the number of myocommata and vertebrae, which have already been noted 

 by Owen, and there are corresponding differences in the number of scales between the 

 points taken. It is not my purpose on the present occasion to deal with points of 

 anatomy, and with regard to the enumeration of scales I will record that it is by no 

 means an easy task in Lepidosiren on account of the delicacy of the scales, their small 

 size and deep implantation, as Well as the abundant coagulated and strongly pigmented 

 tissue which covers them in specimens recently preserved in spirit and therefore not 

 macerated. 



