A CARBONIFEROUS FAUNA FROM NOWAJA SEMLJA. 171 



valves in apposition, reaches a size exceeding that commonly attained by the species ; 

 when complete it probably" measured some 40 mm. in length. As this large specimen 

 shows no trace of the sinus characteristic of Productus punctatus (Martin), we have here 

 another conclusive proof of the fact that Productus elegans is not to be considered as 

 the young stage of Martin's species. 



Productus keyserlingianus de Koninok, var. (PL II. figs. 36-36a.) 

 De Koninck, Monographie du Genre Productus, 1849, p. 134, pi. xiv. fig. 6. 



Four specimens, two of which have both valves in apposition, differ from Productus 

 keyserlingianus as described by de Koninck in having fewer tubercles ; they are other- 

 wise quite like the Belgian form. 



The specimen figured under this name by M. Krotow is remarkable for an unusually 

 large number of tubercles.* 



Productus spinulosus J. Sowerby. (PL II. fig. 30.) 



Davidson, loc. cit., pi. xxxiv. figs. 18, 19. 



The materials are fragmentary, but abundant ; they are quite characteristic, with the 

 exception of one or two specimens which appear to be slightly flatter than the type as 

 refigured by Davidson. 



Sub-genus Proboscidella Oehlert. 



Productus (Proboscidella) nysti de Koninck. (PL II. figs. 34, 34a.) 

 De Koninok, loc. cit., p. 65, pi. xiv. fig. 5. 



Materials indifferently preserved and belonging to this species might easily be taken 

 for brachial valves of other Productids, but the specimen in the collection is in a fair 

 state of preservation, consisting of a nearly complete pedicle- valve with part of the other 

 valve still in apposition. 



Its proportions and ornamentation, and its short bent margin, are exactly as depicted 

 by de Koninck. 



Incert^e Sedis. 



The collection contains two fragmentary pedicle-valves of a Productoid shell, 

 characterised by its greatly depressed shape and the extreme thinness of the test. The 

 ornamentation consists of broad longitudinal folds bearing a few obtuse tubercles, with 

 indications of wrinkling on the ears. 



* Mem. Com. Ge'ol. Russie, vol. vi., 1888, pi. i. fig. 20. 



