104 



GENERA OF THE SUBORDERS ORTHOIDEA AND PENTAMEROIDEA 



one on this genus, and in it he attempts to show the 

 relationship of Pentamerus and Porambonites. In- 

 deed, he considered the relationship so close that he 

 united the two genera in the family Porambonitidae, 

 placing them between the Strophomenids and the 

 Rhynchonellidae. He thought that Porambonites 

 connected the Porambonitidje to the Strophomenidae 

 by way of Orthisina, and that the relationship of the 

 former to the Rhynchonellidffi was shown by the simi- 

 lar internal features in Pentamerus and Camerophoria. 

 While these morphologic comparisons are correct in 

 part, the generic relationships are now seen to be 

 different. 



Hall and Clarke"® found the most direct relation- 

 ship of Porambonites "in those pentameroids which 

 have been designated as Parastrophia and Anastro- 

 fhia." These affinities with the pentamerids have been 

 continued since Noetling's time. Schuchert'" later 

 greatly expanded the Porambonitidje but more re- 

 cently^^ restricted it to Porambonites and Noetlingia. 



Recently Kozlowski'" has also contributed informa- 

 tion on the taxonomy of Porambonites and has con- 

 tinued the pentameroid affinities, placing the shells, 

 however, in the order Telotremata along with the rest 

 of the Pentameracea. This author holds that Poram- 

 bonites has a spondylium discretum, which is rare out- 

 side of the Cambrian genus Huenella, in which a 

 spondylium duplex is produced by close crowding of 

 the dental plates. He therefore sees the origin of 

 Porambonites from Huenella. Kozlowski places in 

 the family, besides Noetlingia, Lycophoria also, but the 

 abnormal orthoid cardinal process of the latter would 

 seem argument enough to exclude this genus from the 

 Porambonitidae. 



The present writers can not subscribe to all the 

 above, and especially do not see how Porambonites 

 can be placed with the Pentameracea, for the following 

 reasons : 



(1) The universal presence in the Porambonitidas 

 of a well defined cardinal area in both valves. This 

 feature is only occasionally well developed in the 

 Pentameracea (Stricklandia, placed here doubtfully). 



(2) The presence of a prominent notothyrium. 



(3) The absence of a spondylium simplex or spon- 

 dylium duplex. This is the most important of the 

 three. 



It has been shown above that even in old age 

 Porambonites never develops a true spondylium, since 

 the structure usually so called is actually only a simu- 

 lation of such through the addition of secondary shell. 

 In other words, the dental and crural plates are blank- 



"'Pal. N. Y., vol. 8, pt. 2, 1895, p. 22 5. 

 '^ Zittel-Eastman Text-book of Paleontology, 2d ed., vol. 

 1, 1913, p. 393. 



" Foss. Cat., Pars 42, 1929, p. 15. 



"Pal. Polonica, vol. 1, 1929, pp. 127, 131. 



eted by adventitious shell uniting in front. It is there- 

 fore our conclusion that Porambonites should be placed 

 in the Orthacea. Verneuil^^ long ago suggested this 

 relationship and Suess' classification of the brachiopods 

 showed the same view. 



The question of the actual genotype of Porambonites 

 is one that needs to be adjusted, but this probably can 

 not be done in America where extensive collections are 

 lacking. Pander never selected a genotype, but David- 

 son, Hall and Clarke, and Teichert have all done so. 

 Davidson,'* the first to select a specific type, chose 

 Terebratulites <equirostris Schlotheim, but since this 

 species was not included in Pander's original list, it 

 may be objected that Davidson's selection rests on inse- 

 cure grounds. In defense of Davidson it may be 

 stated, however, that he chose as genotype a form to 

 which Verneuil had referred eight of Pander's species 

 as synonyms, and thus in a roundabout way actually 

 used one of Pander's species. 



According to Teichert'^ it is impossible to place 

 any of Pander's species in T. wquirostris Schlotheim 

 because almost all of Pander's brachiopods were from 

 formations below the Echinosphsrites limestone, the 

 source of Schlotheim's shell. Furthermore, this lime- 

 stone is not exposed in the vicinity of Leningrad, where 

 Pander collected most of his specimens. Therefore 

 Pander's species belong to Teichert's first and second 

 immigration of Porambonites, whereas P. wquirostris 

 is of the third introduction. For these reasons Teichert 

 believes it is impossible to use Davidson's choice of 

 genotype. 



Hall and Clarke,''" according to the practice usual 

 in their work, selected P. inter^nedia Pander as the 

 genotype since it was the first species named. As 

 Davidson's selection fails to stand according to the rules 

 of nomenclature, that of Hall and Clarke would have 

 to be accepted. However, this would be unfortunate, 

 since P. intermedia is one of Pander's most obscure 

 species, wretchedly figured and poorly described, and 

 as a consequence overlooked in nearly all synonymies 

 and catalogues. 



In view of the above, it is here recommended that 

 Pander's P. intermedia be thrown out as a species 

 because it is so poorly figured and described, and 

 because its retrieval is impossible due to the loss of 

 Pander's types by fire. Elimination of this species 

 will make way for the use of P. reticulata Pander as 

 the genotype of Porambonites, as recommended by 

 Teichert. This is a well known, excellently figured 

 species and will make a fine genolectotype in harmony 

 with all of the old views as to the interpretation of 

 Porambonites. 



" Geology of Russia, 1845, p. 128. 



'* Op. cit., p. 99. 



^^ Private communication. 



'" Op. cit., p. 226. 



