. Brachiopod genera of the suborders Orthoidea and Pentameroidea. Orthoidea; Pentameroidea; Paleontology -- Paleozoic. GENERA OF THE SUBORDER PENTAMEROIDEA 167 Discussion.—Hall and Clarke say:" Whatever may be the oscillation in form and the varia- tion in secondary characters presented by Camarella, Para- strofhu and their allies, present evidence indicates that they must be regarded as the genetic precursors, as they are the secular precedents of the great group of true pentameroids. And on page 355 they erect the family Camerellidre for CamereUa, Parastrophui, Anastrophia, and ? Bran-
. Brachiopod genera of the suborders Orthoidea and Pentameroidea. Orthoidea; Pentameroidea; Paleontology -- Paleozoic. GENERA OF THE SUBORDER PENTAMEROIDEA 167 Discussion.—Hall and Clarke say:" Whatever may be the oscillation in form and the varia- tion in secondary characters presented by Camarella, Para- strofhu and their allies, present evidence indicates that they must be regarded as the genetic precursors, as they are the secular precedents of the great group of true pentameroids. And on page 355 they erect the family Camerellidre for CamereUa, Parastrophui, Anastrophia, and ? Bran- coma; all the other genera referred here by them are now excluded from this family. Table 18 Camerellid^ Anastrophia Parastrophinella. Metacamerella CamereUa 2, ^ Branconia Syntrophiid^ Beecher and Clarke' have shown that in early age the shells of Anastrophia are normally biconvex, and the brachial valve scarcely deeper than the opposite. ... In this condition the form of the shell resembles that of normal individuals of Camarella volborthi, and in this series of forms, beginning in Camarella where senile shells evince a gibbosity of the brachial valve and a tendency toward reversion of convexity, and ending with the Lower Helderberg Anastrophia verneuili, we have a consecutive and gradational development in internal struc- ture, which is accompanied by more abrupt variations in exterior.*" As conceived by the present writers, the Camcrellidx consist of shells in which the dorsal valve is usually more convex than the ventral. The shells are com- monly multicostate. The ventral interior has a promi- nent spondylium duplex, but the most important family *Pal. N. Y., vol. 8, pt. 2, p. 341. » N. Y. State Mus., Mem. I, 1889, p. 32. " Hall and Clarke, op. cit., p. 225. characters arc in the dorsal valve in connection with the cardinalia. The brachial processes are supported by alate plates, concave outward, and these arc, in turn, supported by septal plates which are ci
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