16 



PKOF. E. EAT LANKESTER ON LEPIDOSIEEN AND PEOTOPTEEUS. 



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







Total 



Ratio of total 



Head- 



Ratio of 



Ratio of 



Ratio of 



No. 



Specimen. 



length in 



length to 



length 



inter-membral 



post-pelvic 



cervico-dorsal 







centimeters. 



head-length. 



(unit). 



length. 



length. 



length. 



1. 



Specimen in Oxford Museum, 

 killed, and measured three 

 hours after death (see PI. II., 

 and explanation where this 

 specimen is figured), from the 















2. 





50 



6-25 



1 



2-5 



2-63 



1-3 



Quite small specimen in the 





Oxford Museum 



23 



7-66 



1 



3-3 



3-3 



1-4 



3. 



Prom the Zambesi (British 



















39 



7 



1 



3 



3 



1-2 



4. 



A second from the Zambesi 



















32 



8 



1 



3-25 



3-75 



1-5 



5. 



Stuffed specimen in British 

 Museum, formerly living in 

















the Crystal Palace, Sydenham. 



79 



9-3 



1 



3-53 



4-17 



1-64 



6. 



Very large stuffed specimen in 

 British Museum (purchased 

















of M. Parzudaki) : Nile .... 



90 



7 



1 



3-46 



2-46 



2 



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

 of the figures derived from the stuffed specimens of Protopterus) are, firstly, that the 

 proportional value of the measurements differs greatly in different 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 6J 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 1\ 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 ihe 

 same in the two genera. 



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

 differences in the number of myocommata and vertebras, 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. 



