22 Sir W. Jardine on the Habits of Lepidosiren annectens. 



to such as are now becoming venerable from long duration, 

 have maintained their standard excellence both in illustra- 

 tions and in the high character of communications, and also 

 for the sake of our correspondents in distant countries, it may 

 be right, first, shortly to run over the history of this singular 

 genus, and the results at which Mr. Owen has arrived :n his 

 recent examinations. 



The genus Lepidosiren was formed by Professor Natterer, 

 from an animal discovered in the rivers, or rather in the 

 swamps of South America. Two specimens only were ob- 

 tained; the one was found in a swamp on the left bank of the 

 river Amazon, the other was taken in a pond near Borba, on 

 the river Madeira, and they were described in the ' Annals of 

 the Museum of Vienna,' under the generic title above named. 

 In 1837, specimens of a remarkable animal were brought from 

 another continent, the vicinity of the river Gambia, in West- 

 ern Africa, by Thomas C. B. Weir, Esq. ; and one of them 

 being presented to the Royal College of Surgeons in London, 

 has served Mr. Owen for the account which has just now 

 been published*. 



In its skeleton the Gambia species is partly osseous, partly 

 cartilaginous; the bodies of the vertebrae, for instance, are 

 not ossified. The articular surface of the lower jaw pre- 

 sents a more complicated structure than is usually observed in 

 Fishes and Reptiles. The ribs are thirty-six pairs, all simple, 

 slightly curved slender styles. The tentacles or rudimentary 

 fins are many-jointed ; the colour of the bones is green, and 

 altogether it offers a most singular and interesting combina- 

 tion of the cartilaginous and osseous types. The muscles of 

 the trunk present all the simplicity and uniformity charac- 

 teristic of the class of Fishes. There are no pancreatic caeca. 

 The intestine is traversed throughout by a spiral valve. The 

 branchiae resemble in form those of the Siren, consisting of 

 separate elongated filaments, attached only by one extremity 

 to the branchial arch ; but these extremities are fixed directly 

 to the branchial arch, and not to a common pedicle extended 

 therefrom, as in the Siren. Viewed with a moderate lens, the 

 tripinnatifid structure is beautifully seen in each branchial 

 filament. Thus, although these organs correspond in all es- 

 sential points with those of the true Fishes, yet the gills ap- 

 proximate, in then- filamentary form, to those of the Perenni- 

 branchiate Reptiles. The female organs of generation present 



* When making out the elaborate Catahjgue for the learned body to 

 which he belongs, the generic name of Protoplerus suggested itself, but the 

 perusal of Dr. Natterer's paper led him to believe that it was generically 

 identical. 



