﻿Vol. 66.~] XOX-MARINE MOLLUSCA, ETC. FROM NYASALAND. 243 



Prof. Amalitsky has specially studied this molluscan fauna, and has 

 noted its resemblance to that of the Permian beds of Russia, 

 five species of the shells being determined as common to these 

 two widely distant areas. The distribution of these genera is set 

 out in a subsequent table (p. 246). 



Genus Pal^omutela, Amalitsky. 



'Ueber die Anthracosien der Permformation Russtands' Palseontographica, 



vol. xxxix (1892) pp. 159, 199. 



Types = P. verneuili & P. keyserlingi, Arnalitsky. 



Synonyms : Iridina (?) Sharpe, 1856 ; Iridina (?) T. R. Jones, 1890. 



Distribution. — The Permian of Eastern Russia and the 

 Karroo Formation of South Africa [ = Permo-Carboniferous]. 



Pal^omtitela oblonga (T. R. Jones). (PI. XIX, figs. 11-14,) 



Tellinidae (species of the), H. Drummond, 'Tropical Africa' 1888, p. 192. 

 Iridina (?) oblonga, T. R. Jones, Geol. Mag. 1890, pp. 556-57 (woodcut). 

 Palceomutela, W. Amalitsky, Palteontographica, vol. xxxix (1892) p. 159 ; and 

 Quart. Journ. Geol. Soc. vol. li (1895) p. 341. 



The specimens referred to this species are fairly well represented 

 in a dark shaly matrix, but consisting chiefly of natural casts, like 

 those originally described by Prof. Rupert Jones from Maramura, 

 in which a dentition can be deciphered. With the view of testing the 

 presence of teeth, on which the adoption of Palceomutela would depend 

 as opposed to the edentulous genus Palceanodonta, a surface has 

 been prepared of the dorso-posterior region of aright valve, showing 

 a thickened hinge-plate anteriorly but becoming more slender 

 towards the posterior end. The marginal lines of this hinge enclose 

 a series of narrowly angulate and acute >-shaped teeth, generally 

 suggestive of what is present in Palceomutela, although of greater 

 obliquity (see PI. XIX, fig. 13). On such evidence, the species 

 oblonga is retained in Palceomutela, where Prof. Amalitsky grouped 

 it when prosecuting his investigations on these freshwater shells 

 without, however, the aid of dental characters at that time. 



The valves vary in length from about 5 to 15 millimetres, being 

 therefore somewhat smaller than those from Maramura, which 

 exhibited a maximum length of 20 millimetres. One of the right 

 valves still shows mineralized remnants of an external ligament 

 reposing in a narrow elongate, lanceolate depression. 



The specimens correspond with the original details of this species 

 as expressed by Prof. Rupert Jones : — 



' The shells are oval-oblong, or sub-oblong, rounded at the ends unequally ; 

 the posterior being somewhat truncate, and the anterior obliquely truncate, 

 with an oges-curve below the umbo. Hinge-line long and straight ; ventral 

 margin slightly curved. Various degrees of imbedment affect the visible shape ; 

 some individuals showing only a triangular outline. The surface \s moderately 

 convex, and bears rather strong concentric lines of growth. These fossils have 

 a general resemblance to the Iridina described and figured by D. Sbarpe in the 

 Trans. Geol. Soc. ser. 2, vol. vii, pp. 225, 226, pi. xxviii, tigs. 2-4. These were from 

 the Karroo Formation at Graaf-Reynet in the Cape Colony.' (Loc. supra cit.) 



The Maramura specimens were first referred to by their discoverer, 



