140 PALEONTOLOGY OF NEW YORK. 



dental sockets. The brachidium consists of loosely coiled spirals of about four 

 volutions, the cones having their apices directed toward the lateral margins of 

 the valves. On the dorsal side the primary lamellae are close together, but on 

 the ventral side they are wide apart, this fact indicating that the bases of the 

 spirals do not lie in parallel planes but converge toward the brachial valve, so 

 that the slope of the cones, which are somewhat appressed laterally, is essen- 

 tially that of the lateral slopes of the pedicle-valve. The character of the loop 

 has not been ascertained. The muscular impressions consist of four distinct 

 adductor scars which are separated medially by a low, thin ridge. 



Surface of both valves covered by a few coarse plications, continuous from 

 the umbones to the margins. Of these there are four or five on the lateral 

 slopes. On the pedicle-valve the median pair is the strongest, and forms a sort 

 of double fold with a low sinus between them. On the brachial valve there is 

 a corresponding low median sinus, which contains a simple or double plication. 

 The exterior is covered with fine elevated radiating lines which are usually 

 interrupted to form radiating rows of elongate, lachrymiform pustules. 



Shell substance fibrous, impunctate. 



ViTDLiNA now takes its place quite naturally in close association with Ccelo- 

 SPIRA and Leptoc(ELIA. Yet the remarkable development of the cardinal area 

 on both valves and the great open delthyrium are features which suggest an 

 alliance with the orthoids. In so late a representative of this group of 

 spiriferous genera the occurrence of these characters may probably be inter- 

 preted as a single recurrence of an early phase of development. 



Like the genus Tropidoleptos, with which Vitulina is closely associated 

 wherever it occurs, the latter appeared suddenly, attained a very prolific develop- 

 ment, and as abruptly disappeared. In South America it appears with Tropido- 

 lepttis carinatus wherever Devonian faunas have been recognized, and perhaps 

 more abundantly in the lower Devonian, in association with Leptocalia palmata, 

 Salter, or L.flabellites, Conrad, than in those faunas considered equivalent to the 

 Hamilton shales of New York. Dr. 0. A. Derby, in reporting the species from 

 the Province of Matto Grosso, Brazil, says : " This generic form would seem to be 

 peculiarly a South American one, since, while it is rare and only very locally dis- 



