106 



GENERA OF THE SUBORDERS ORTHOIDEA AND PENTAMEROIDEA 



the character of the dental plates and the peculiar 

 fusion of the brachiophore plates with the cardinal 

 process, are sufficient to distinguish this shell from all 

 known brachiopod genera. 



Discussion. — Before proceeding to a discussion of 

 the taxonomic position of Lycophoria, it will be neces- 

 sary to summarize certain of its characters. The 

 dental plates are subparallel or slightly divergent, but 

 never do they unite medially, or even remotely resem- 

 ble a spondylium, although Kozlowski thinks the mus- 

 cle pit with its high margins resembles his spondylium 

 discretum, a feature more common in occurrence than 

 he supposed. Furthermore, one does not see in these 

 shells any great thickening of the dental plates as 

 occurs commonly in Poramhonites. The mantle of 

 Lyco-phoria filled up the umbonal cavities and also 

 placed a considerable deposit of adventitious material at 

 the back end of the delthyrial cavity, causing the mus- 

 cles to migrate forward, but there is no extensive thick- 

 ening of the plates themselves. Judged from the ven- 

 tral valve, alone, one might be inclined to place these 

 shells with Pora>?ibonites, as Kozlowski has done, but 

 the dorsal valve shows departures too radical to justify 

 this reference. 



In the dorsal valve, the cardinalia and the muscle 

 impressions are the chief structures of interest. The 

 "cardinal process," so called, consists of four distinct 

 parts: (1) the chilidium, (2) the cardinal process 

 proper, (3) the brachiophores, and (4) the "crura." 



( 1 ) The chilidium is a thick, subcircular plate lying 

 over the base of the cardinal process, bent ventrally 

 on both sides and also dorsally at the front end. It 

 reminds one much of the chilidium of Productorthis 

 (see pi. 4, fig. 16). 



(2) The cardinal process is more difficult to indi- 

 vidualize. At its front end it is crescentic or lunate 

 in outline, and extends under the ventral beak. In 

 some specimens its ventral surface bears a rather deep 

 groove. However, the process is clearly single, never 

 being bifid at its front end as in Derbyia, Triflesia, or 

 Meekella. In other words, the cardinal process, 

 although much modified, is essentially orthoid. 



(3) The brachiophores show as obscure plates con- 

 vergent toward the roof of the valve and possibly 

 uniting at their bases. These have been crowded 

 together and have fused with the cardinal process at 

 their posterior extremities (see pi. 14, fig. 30). The 

 sockets are deep and excavated into the shell substance, 

 and bear a small tooth on the outer wall above the 

 excavation noted before. The curved posterior ex- 

 tremity of the tooth fits into the excavation and the 

 small tooth articulates with the deep socket on the 

 posterior face of the ventral tooth. 



(4) The crura are long processes extending from 

 the brachiophores on each side of the cardinal process. 



They have a slight hollow groove toward their dorsal 

 ends and appear as folded plates. 



The taxonomic position of Lyco-phoria is difficult to 

 express. Lahusen would place it with the Stropho- 

 menida:, but in current classification it has been allied 

 doubtfully with the Parastrophininas. Kozlowski^^ 

 would place it with Poramhonites in the Porambon- 

 itidffi. Strophomenoid affinities are said to occur chiefly 

 in the cardinal process, which, according to Hall and 

 ClarkeV^ section is described as strongly bifid. How- 

 ever, the writers have been unable to find a bifid car- 

 dinal process. If Hall and Clarke's section were cut 

 obliquely across the beaks so as to bevel the cardinal 

 process transversely or obliquely, the tapering of the 

 antero-ventral ends of the ventral groove would give 

 the appearance of a bifid process. None of Lahusen's 

 figures, nor any of the excellent interiors in the Schu- 

 chert Collection, give any indication of a bifid cardinal 

 process. Hall and Clarke thought that the cardinal 

 structure allied this genus to the orthids but that 

 "Atrypa micella adds to these orthoid features the 

 cardinal process of a streptorhynchoid, like Triplecia 

 and Mimtdus, thus presenting another point of tan- 

 gency between these shells and the pentameroids." 



Schuchert has persistently classified this genus, al- 

 though with a query, with the pentamerids, allying it 

 always with the Parastrophininas. However, there is 

 no pentamerid feature in Lycophoria save the biconvex 

 valves. Kozlowski placed it in the Porambonitidas, 

 referring this family to the Telotremata. It has been 

 shown — and a glance at the figures (pi. 14) will con- 

 firm this — that no characteristic pentameroid features 

 occur in Lycophoria. Furthermore, we have removed 

 the Porambonitidae from this association and referred 

 them to the Orthacea. The same reference, but as a 

 separate family, is suggested for the genus now under 

 consideration, since it shows orthoid features in the 

 ventral interarea, open delthyrium, and discrete dental 

 plates. In the dorsal valve it has been shown that the 

 cardinalia have developed, by growing inwardly and 

 fusing with the brachiophore supports, a cardinal 

 process and chilidium. These features could be devel- 

 oped by the lateral crowding of such cardinalia as are 

 seen in Productorthis, but we are not holding that 

 Lycophoria descended from that genus. 



The dorsal valve of Lycophoria thus forms a con- 

 vergence toward the type of cardinalia so well known 

 in Meekella and Derbyia of the Carboniferous. Lyco- 

 phoria and Productorthis of the Middle Ordovician 

 are therefore two stocks that have independently orig- 

 inated characters that are re-developed in other stocks 

 {Derbyia and Productus) in the Pennsylvanian. 



"Pal. Polonica, vol. 1, 1929, p. 131. 



" Pal. N. Y., vol. 8, pt. 2, pi. 62, fig. 5 3. 



