Miscellaneous. 349 



part this surface is smooth ; its lateral surfaces have a colourless, soft, 

 velvety aspect, and with a lens, crowded, small, shaggy prolongations 

 are perceptible, in which the arteries and veins of the gills ramify. 

 These vessels are elongations of the vessels of the inner gills ; we find 

 them also at the posterior part of the gill-aperture, between the upper 

 end of the gill-arches and the external gills beneath the skin cover- 

 ing the gill-aperture : they are five, three arteries and two veins. 

 One of the arteries arises from the second aortic arch ; the two others 

 are the continuation of the extremities of the gill- arteries of the first 

 and middle of the three posterior and internal gills. The two other 

 vessels, which return the blood from the external gills, terminate in 

 the gill-veins of the first and second of the three internal and poste- 

 rior gills, after they have separated from the superior extremity of 

 their gill-arches. The most anterior gill, at the anterior margin of 

 which the gill-cavity is situated, and is separated by a cleft from the 

 most anterior of the two gill- arches which are unfurnished with gills, 

 is a true respiratory gill, and thus represents the supernumerary 

 respiratory gill of the cartilaginous fishes, not the pseudo-branchia 

 of other fishes. It receives a branch of the gill-artery and gives off 

 superiorly a gill-vein, which corresponds to the carotis anterior. It 

 is however remarkable that the artery of the most anterior gills, al- 

 though it arises in the same manner as the other gill-arteries, yet 

 before it enters the gill gives off a branch for the nutrition of the 

 body, which is distributed to the inferior aspect of the most anterior 

 part of the head, to the skin and muscles of this part ; a fact which 

 is unique in ichthyology, and can only be explained from the gill- 

 arteries of the heart conveying not only dark red but also partly 

 bright red (arterial) blood, which is transmitted from the lungs to 

 the heart. The auricle of the heart is single. The spleen of the 

 Lepidosiren has hitherto been overlooked. It is large, and lies be- 

 hind the stomach and commencement of the intestinal canal, beneath 

 the peritoneal coat of the tractus intestinalis. It must be separated 

 from the black pigment which forms a copious substratum beneath 

 the peritoneal covering of the intestines. The lateral anus is not 

 always situated on the same side, being in some on the right, in 

 others on the left. 



Should Lepidosiren annectens and the fish of Quellimane belong to 

 diflferent genera, which is not probable. Dr. Peters proposes Rhino- 

 cryptis amphibia for the name of the latter. A circumstance which is 

 much in favour of their identity, and renders it probable that we are 

 not perfectly acquainted with Lepidosiren annectens, is, that this has 

 been lately observed by Jardine * also to have filaments on the pectoral 

 fins ; these were mistaken by Jardine for accessory fin-rays. 



The next point to be determined is, whether the cartilaginous fin- 

 rays found in the fish of Quellimane are present in Lepidosiren an- 

 nectens. Then comes the question, whether these and the external 

 branchial filaments are also present in Lepidosiren paradoxa. Upon 

 this will depend whether the African fish, although identical in genus, 



* Ann. of Nat. Hist. vol. vii. p. 24. 



