NO. 1557. NEW CHINESE PALEOZOIC FOSSILS— GIRTY. 45 



BRACHIOPODA. 



SPIRIFER BLACKWELDERI, " new species. 



This form has been obtained at two localities, and occurs in consid- 

 erable alnindance in the shape of casts of separate valves. The fol- 

 lowing characters have been observed: 



De><crlpt'wn. — The shape of the ventral valve is subquadrate. The 

 convexity is high, the beak large, erect, gibbous. The area is well 

 defined, high, and concave. The foramen is large, its width at the 

 base being almost one-third that of the whole area. The cardinal 

 angles are rounded and the cardinal line considerably shorter than the 

 greatest width. A narrow and moderately deep sinus traverses the 

 shell, becoming gradually broader and less well defined toward the 

 front. The sinus is not divided b}^ plications, nor do an}" ribs mark 

 the sides. On the interior there are two strong dental plates, but no 

 septum. 



The dorsal valve is transversely subelliptical in outline. The car- 

 dinal extremities are rounded, and the hinge line is shorter than the 

 greatest width. The beak is small and depressed. A moderately 

 high, rather well-defined mesial fold passes downward, gradually 

 widening in its course. 



The surface lacks ribs either upon the sides or on the fold and 

 sinus, but is marked by very fine radiating strife. 



I know of no Carboniferous species which reall}^ requires compari- 

 son with the present. In general appearance it suggests a Rdicidaria^ 

 such as R. Ilneata, but the fine, continuous, lira' can hardly be inter- 

 preted as marks left hy the spines which characterize that group. 



The development of fine sul)sidiary line seems to be a much more 

 common feature in the English Rettcularias (see R. llneata var. 

 reticulata), judging from Davidson's description and figures, than in 

 the American, where it is essentially unknown. We have at least one, 

 though a little known, form possessing this character, which was 

 apparently described by Swallow as Spirujera jrt'oat!. 1 am not pre- 

 pared to speak positively as to the internal structure of this type, but 

 dental plates and septa seem to be absent or but slightly developed. 

 In the American RetlcuJavlas (R. pseadolineata^ etc.), and I suppose 

 in the European ones, there is a median septum in both valves, while 

 the ventral valve possesses long dental plates as well. The Chinese 

 shell thus difl'ers in structure from the Jineatas group of Sjnrlfers^ 

 although it shows some points of superficial resemblance. 



iS'. hiackioehlerl difi'ers from S. Uneatus as identified by Kaj^ser from 

 Chinese specimens, as well as from any other Chinese species identi- 

 fied or described by him, nor can it be found among the shells de- 



«This species is named for Mr. Eliot Blackwelder, 



