1894. PROCEEDINGS OF TJSE NATIONAL MUSEUM. 721 



the teeth. In the braeliial valve the cardinal plate is divided medially 

 by a sinus. The cardinal process is obsolete, and the medial septum 

 either wholly absent or represented only by a short, low ridge not 

 attached to the cardinal buttresses, and not extending forward into 

 the cavity of the valve between the buttresses. As Euilesia is much 

 the older name it must be retained for these forms, unless Macandrevia 

 exhibits characters strong enough to give it generic independence. 

 So far as known, the only differences between them consist in the 

 smooth surface of the valves and the feebleness of the brachial septum 

 in Macandrevia. These can hardlj^ raise the latter above subgeneric 

 rank, as the plication of the valves is often inconstant in the same 

 species, while the same species (and doubtless the same individual) at 

 different ages will show a septum more or less developed, from quite 

 obsolete in the young, to quite perceptible in the senile stag'e. I have 

 verified this on the type of Macandrevia^ though the septum is never 

 j)rominent. If the beak of the brachial valve of an old individual 

 were to be ground off, a septum woiild be perceptible there very much 

 as figured by Oehlert for the beak of Eudcsia eardium. Consequently 

 I feel obliged to regard Macandrevia, at least for the present, as form- 

 ing merely a subgeneric groui> under the genus EudeMa. As regards 

 the partly austral species about to be described, since there is no means 

 of deciding whether their development agrees with those forms referable 

 to JMagellaniime or not, and as the adnlt shells exhibit no characters 

 which could be regarded as diagnostic of a genus different from 

 Endesia, I feel obliged for the present to refer them to that group. It 

 may be observed that there is nothing to prevent the free migration of 

 northern forms into the south Pacific along the coast of the Americas. 

 The writer lias already the evidence to show that several species, in 

 deep water, do extend from Bering Sea south to the vicinity of the 

 Galapagos Islands and, in the case of one species, Solemya joh7isoni, 

 Dall, more than a thousand miles farther south, with the known great 

 range of many brachiopods, there would be no apparent reason why 

 species of the Panamic region, for instance, belonging to the northern 

 type of development should not extend their range southward, if 

 o|)i3ortunity arose. I regard it then, as quite likely, that the sj)ecies I 

 refer to may be Macandrevian in their development as well as in their 

 adult state, though, for the mass of characteristically austral species, 

 the reverse might be the case. 



Subgenus Macandrevia, King. 



Type Tercbratida cranhiiH, ^liiller. 



MACANDREVIA AMERICANA, new species. 



Plate XXXII, figs. 1,4,7. 



Eudcsia foniabieana, Dall (not Orbigny) Proc. U. S. Nat. Mus.,xii, 1880, p. 231. 



Shell of moderate size, rounded ovate, brownish white, smooth exter- 

 nally except for numerous incremental lines best visible under a lens; 

 margins not flexuous; pedicle valve moderately arched, thin, with a 

 Proc. N. M. 91 40 



