BRACHIOPODA. 
9 
“ Oryctographie du Gouvernement de Moscou ” (1830), is Choristites Mosquensis, 
Fischer (= Spirifer Mosquensis, de Verneuil). The generic term was based upon 
the existence in the pedicle-valve of highly developed dental plates extending 
almost or quite to the anterior margin ; a character which has a less prominent 
development in a few other species, some of which, as for example, Spirifer 
plicatellus, cannot be satisfactorily grouped with Mosquensis on the basis of 
external characters. The greater or less prolongation of these septa or dental 
lamellae will be found a feature of comparatively little taxonomic value among 
these fossils. 
Delthyris, Dalman, 1828.* Dalman divided the genus Spirifer into Del- 
THYRis and Cyrtia, citing as his first example of the former, Delthyris elevata, 
Dalman, a species now well known in the European Silurian, and one of the 
plicate-firnbriate members of the genus. The name Delthyris may, with a 
restricted interpretation, have a value equivalent to that of Reticularia, McCoy, 
under which the nonplicate-fimbriate species may be included. 
McCoy, in his “ Synopsis of the Characters of the Carboniferous Fossils of 
Ireland ” (1844), proposed a number of new names to subdivisions of the family 
Delthykid^ : 
Fusella {op.cit.,p. 132); type, Spirifer fusiformis, Phillips-, a small, transverse 
shell with smooth, rounded ribs, some of which are stated to occur on the me¬ 
dian fold. The species is but little known, Davidson statingf that he had seen 
only the imperfect original in the collections of the British Museum. 
Martinia (pp. cit., pp. 128, 139). “ Gen. Ch .—Hinge-line shorter than the 
width of the shell; dorsal edges of the cardinal area obtusely rounded ; surface 
smooth ; spiral appendages small.” 
This group is excellently characterized, though McCoy was in error, as shown 
by Mr. Davidson and the Rev. Mr. Glass, in considering the spirals as having 
a less development in proportion to the dimensions of the shell than in other 
Spirifers. De Koninck, Davidson, Waagen and others have observed that the 
epidermal layer of the shell is minutely punctured. The first species which 
^ Kongl. Vetenskaps Akad. Handlingar, pp. 93, 99. 
t British Carboniferous Brachiopoda, p. 57. 
