14 PEOF. E. EAT LANKESTEE ON LEPIDOSIEEX AND PEOTOPTEEUS. 



propose to point out what are the chief differences of form and proportion between 

 Lepidosiren and Protopterus as represented on the one hand by the Paraguay specimens 

 of Lepidosiren, and on the other hand by specimens of Protopterus from both the 

 Gambia and the Zambesi. 



Sir Eichard Owen, in his original description of Protopterus annectens (Trans. Linn. 

 Soc. xviii. 1841, p. 327), pointed out important differences in his new form from Africa 



depending as they do on the general form of the head and snout, which is liable to distortion owing to the 

 specimen resting on the head when placed in a jar containing the alcohol in which it is preserved. The males, 

 both of the series assigned to the old species, L. paradoxa, Fitz., and of the series assigned by Ehlers to his 

 new species, presented equally the remarkable viUi on the pelvic limbs hitherto unknown in Lepidosiren. In 

 the females of both the villi are absent — the specimens brought home formerly by Natteror were females. 



The only character which Ehlers adduces for separating the Paraguay specimens into two distinct species,, 

 which seems to me likely to be of value, is that upon which he bases the specific name ' articulata.' 



One (or more ? Prof. Ehlers does not state) of the specimens belonging to the series of twenty-seven, which 

 on account of shape of head and colour he had set apart as a new species distinct from the remaining five, was 

 found to exhibit a segmentation of the cartilaginous skeletal axis of the limbs, both pectoral and pelvic. Now 

 it is well known that according to Hischoflf's description and figure the skeletal axis of the limb (of each girdle} 

 of L. paradoxa, Fitz., is an unsegmented continuous tapering rod of cartilage. In the African Protopterus the 

 corresponding skeletal element consists of successive segments. 



As Prof. Ehlers justly observes, the character which he has thus put forward requires testing on a large 

 number of specimens. It does not appear from his statement that he has so tested it. It would not even follow 

 that two species of Lepidosiren exist side by side in Paraguay, because some specimens are found to have 

 segmented skeletal axes to the limbs, and a certain proportion are found to have an unsegmented axis. 



The fact is that the specific determination of the Paraguay Lepidosiren has yet to be made by comparison,. 

 either with the five specimens from the Amazons now in European Museums (one in Paris, two in Vienna, two 

 in Florence), or with new specimens to be obtained from the Amazon system. (See postscript, p. 20.) 



Prof. Ehlers's identification of five specimens, out of thirty-two brought by Dr. Bohls, with L. pxiradooca, 

 Fitz., cannot be regarded as resting on satisfactory grounds, any more than the separation of the other 

 twenty-seven specimens as a distinct species. That one of the latter had a jointed axis to the limb cannot be 

 held to go very far ; we do not really know at present whether such jointing is common, or occasional, or never 

 present in Lepidosiren annectens, and until we do it will be best to consider Dr. Bohls's specimens from 

 Paraguay provisionally as identical with the Amazonian L. annectens, Fitz. (See, however, the postscript to 

 this paper, p. 20.) 



Bischofi^'s figure and description of the cartilaginous axis of the limb of L. annectens, Fitz., in the 'Annales 

 des Sciences Naturelles,' 1840, does not justify a final conclusion as to the absence of segmentation in that 

 axis. Protopterus with its corresponding segmented axis was not known at the time, and in an insufficiently 

 cleaned preparation it is possible that segmentation may have escaped Bischofi''B notice. He makes no emphatic 

 statement on the subject. 



I am unable to gather from Prof. Ehlers's statement whether he he has actually seen a Lepidosiren with an 

 unsegmented cartilaginous axis to the limb, or whether he is merely quoting and assuming the finality of 

 Bischofi''s statement. He says : " Bei dem von mir so gedeuteten Thiere (£. annectens) ist aueh das Skelet der 

 Gliedmassen ein einfacher ungegliederter Knorpelstab." Among Dr. Bohls's specimens there were five " so 

 gedeutet " by Prof. Ehlers. It would be satisfactory to know whether all five, or how many, were ascertained 

 to have the simple unsegmented cartilage-axis, or whether any specimen at all ivas really ascertained by 

 Prof. Elders to exhibit " ein einfacher ungegliederter Knorpelstab " as the fin-skeleton. 



