84 



PALAEONTOLOGY OF NEW YORK. 



or the allied genera. Though Mr. Davidson, in all his citations of the species, 

 was in doubt as to its generic character, he did not manifest an inclination 

 to adopt Mr. Salter's name; but from our present knowledge it seems 

 that the term Monobolina must be accorded recognition. Externally the 

 valves are covered with strong radiating strise, as in the brachial valve of 



SCHIZOCEANIA. 



Genus NEOBOLUS, Waagen. 1885. 



1885. Neoholus, Waage.n-. Memoirs Genl. Surv. India: Salt-Range Fossil?, pt. i, vnl. iv, fa-s. f>, p. 7.56. 



Types, Neobolus Warthi, Waagen, loc. cit., p. 75S, pi. 84, figs. 3-8. 

 N. Wynnii, Waagen, loc. cit., p. 759, pi. 85, figs. 1, 2. 



This peculiar genus from the primordial beds* of the Salt Eange of India, 

 presents some important deviations from the oboloid type of structure. 



In general form and outline the shell is 

 oboloid with a somewhat transverse pos- 

 terior margin, which is slightly thickened, 

 and in the pedicle-valve is traversed by a 

 broad, cross-striated pedicle-groove. The 

 cardinal muscular scars lie close upon this 

 groove ; the central scars are fiiint, and in 

 the figure indistinctly defined, but are seen to abut against " a short thickened 

 ridge or knob" in the middle of the shell. Most striking are the broad mar- 

 ginal scars occurring on both valves, and which appear to represent the external 

 scars in Obolus, and the crescent in Dinobolus and its allies. In the brachial 

 valve a strong longitudinally grooved callosity lies just within the cardinal 

 margin, and this is more or less distinctly continued into a median septum. 

 The arrangement of the muscular scars other than those referred to, is not 

 fully understood. 



Neobolus Warthi. 

 After Waagen. 

 Fig. 39. Interior of pedicle-valve. 

 Fig. 40. Interior of brachial valve. 



* See remarks on page 29. 



