GENERA OF THE SUBORDER ORTHOIDEA 



121 



sion of dalmancllids, namely, Wattsella Bancroft, rep- 

 resented, among others, by two species, D. edgeivood- 

 frisis Savage and D. trstudinarM Dalman, both of 

 early Silurian age. Obviously the confusion caused 

 by so designating the genotype for a group of shells 

 that Hall and Clarke never had in mind would be 

 unjust to those two authors, and would offset any 

 advantage obtained by classifying the biological 

 properties. 



Looking at the nomenclatorial problem in another 

 way, it can be justly contended that Hall and Clarke 

 did not have before them typical examples of Dalman's 

 Orthis testutiifwria, but American shells that had from 

 the beginning been erroneously identified as this 

 species."" Therefore O. testudhwria of American 

 authors in general and specifically of Hall and Clarke 

 is not the same as O. testudinana Dalman of Sweden. 

 Accordingly, one of the several species figured by Hall 

 and Clarke under this name can be selected as the type 

 of the genus, and we now select as the genotype of 

 Dalmanella the specimens illustrated by them on plate 

 5B, figures 27-31, which are of Sardeson's Orthis 

 rogata. 



It may be objected by "legalists" that this pro- 

 cedure is invalidated by Schuchert's having named 

 O. testud'mnria Dalman as the genotype of Dalmanella 

 in his work of 1897,*' a procedure in which he was 

 followed by many others. This objection is granted 

 willingly and would be valid if O. testudinaria Dalman 

 were a native American shell, as pointed out before. 

 Schuchert et al. never questioned Hall and Clarke's 

 identification of the species; it was then the order of 

 the day everywhere to identify similar shells as O. testu- 

 dinaria Dalman throughout the Ordovician. It can be 

 contended, further, that the followers of Hall and 

 Clarke, by using their name unchallenged, did not 

 alter the instability of the identification. 



In further support of the contention that Hall and 

 Clarke did not base their group discussion on O. testu- 

 dinaria Dalman is the excellent work of Sardeson 

 (1897) in which he describes as new species Dal- 

 manellas usually referred to O. testudinaria. He 

 says (p. 106): 



None of the above described species are like, or similar 

 to, Dalman's figures, and to the best of my knowledge, there 

 is ample room for preference of Meck's view, that our forms 

 may none of them be identical with those described as 

 Orthis testudinaria by Dalman, or those identified with that 

 species in England. 



'- We have learned from Doctors Reeds, Croneis, and 

 Rucdcmann, curators of the Hall material in the American 

 Museum of Natural Histor\', the Walker Museum of the 

 University of Chicago, and the New York State Museum, 

 respectively, that there are no specimens of O. testudinaria 

 Dalman in these collections from Borcnshult, the type 

 locality. 



»' Bull. 87, U. S. Geol. Surv., 1897, p. 199. 



Raymond"^ corroborates this statement in the re- 

 mark that ". . . . no one seems to have proved that the 

 real Dalmanella testudinaria is found in America." 

 The present study, moreover, shows that Dalman's 

 species actually has an internal structure totally distinct 

 from that of D. testudinaria Hall and Clarke = D. 

 rogata (Sardeson) and is deserving of a different 

 generic designation. 



Onniella Bancroft (pi. 17, figs. 1, 6, 8, 9, 11, 12, 

 18) has essentially the same internal structure as Dal- 

 vianella (emend.), but differs chiefly in being more 

 transverse and having a somewhat different ornamen- 

 tation. We do not consider these external details of 

 generic value and therefore place this genus in the 

 synonymy of Dalmnnella (emend.). Should Paleon- 

 tology progress to the point where ribbing characters are 

 considered of value in genus making, it would probably 

 be found that Dalmanella meeki will also conform to 

 the characters of Onniella. 



Dalmanella emacerata and D. ignota are among the 

 few Paleozoic brachiopods in which nearly the full 

 complement of muscle-scars has been observed (see pi. 

 17, figs. 19, 22). Sardeson figures (his pi. 5, fig. 6, 

 of ignota) a specimen showing, besides the diductor, 

 adductor, and adjuster scars, two small accessory 

 diductor scars. The specimens that Sardeson studied 

 are now in the Schuchert Collection and there can be 

 little question as to the presence of these marks although 

 they can not be seen so clearly as the figures would 

 indicate. They are not isolated but are continuous 

 with the diductor scars. They may actually represent 

 the back end of the diductor impression rather than 

 separate and special scars. The adductor marks, as in 

 many other genera, are individually semielliptical but 

 together form an elliptical or oval impression super- 

 imposed over the adductor track. 



In the dorsal valve the brachiophores have no fulcral 

 plates and this differentiates the true Dalmanella from 

 Wattsella and Idiorthis of the Wattsellidas, at least so 

 far as the dorsal valves are concerned. The simple, 

 bladelike brachiophores may become spoonlike by the 

 development of adventitious tissue on their inside sur- 

 face, and then they become attached to the dorsal sur- 

 face of the valve; the true brachiophore plate may in 

 that event be almost completely obscured. A common 

 mature and old-age condition is a growth of shell sub- 

 stance over the cardinal process, both shaft and myo- 

 phore ; and in extreme instances the adventitious shell 

 may completely fill the notothyrial cavity and encroach 

 on the brachiophores. 



Dalmanella tcrsa is diflncult to place, since its ex- 

 terior and cardinalia are much like those of Rhipidom- 

 ella. Furthermore, in the ventral valve the diductor 

 scars show a marked tendency to enwrap the adductor 

 field. The species is thus intermediate between Rhipi- 

 domella and Dalmanella, and is believed to indicate 

 the probable origin of Rhipidomella. 



"Geol. Surv. Canada, Bull. 31, 1 92 1, p. 14. 



