390 



ECHIN0LAMP1D.E. 



This definition unfortunately embraces forms which appertain to several genera. 

 Even the three species figured as EcJnnanthus, in Tab. iv, of Breynius's work, from the 

 position of the vent, represent two distinct types. 



The EcHiNOLAMPiDiE resemble the Echinobrissid^ in the general organization of 

 their test ; but the species are distinguished from those of that group by the position of 

 the vent, the development of the peristomal lobes, the basal ambulacral rosette, and by the 

 tubercles, in some genera at least, being perforated. 



In the following table I have given a short diagnosis of the genera, and include in the 

 family Echinolampid^, together with their stratigraphical distribution in time. 



A Table showing the Classification and Distribution of the Echinolampid^. 



Family. Diagnosis. 



Test, oblong, inflated ; petals long, narrow, 

 nearly reaching the border ; vent trans- 

 verse, supra-marginal. 



Test oblong, depressed ; petals short, nar- 

 row, limited to the dorsum; vent oval, 

 marginal, or supra-marginal. 



Test ovoid or discoid ; petals wide, long, 

 nearly reaching the border ; vent, trans- 

 verse, infra-marginal. 



Test large, discoidal, or elevated ; petals 

 large, long, reaching the border ; vent 

 infra-marginal, longitudinal, surrounded 

 by a distinct area. 



Test oblong, depressed ; petals long, nar- 

 row, reaching the border ; vent longitu- 

 dinal, marginal. 



Test elevated, or conical ; petals narrow, ■ 

 lanceolate, short, limited to the dorsum ; 

 vent small, transverse, without area ; base 

 flat, without elevation. 



Test large, oval or circular, much elevated, 

 or conoidal ; petals long, straight, wide, 

 equal, not contracted below ; vent infra_ 

 marginal, triangular ; base flat. 



Genera. Formation. 



Pygorhynchus, Agassiz. Tertiary. 



EcHiNANTHUs, Brei/tiius. Tertiary and Upper Creta- 

 ceous. 



Echinolampas, Grei/. Living and Tertiary. 



Pygurus, Agassiz. 



Cretaceous and Oolitic. 



BoTRioPYGUS, D'Orbigny. Cretaceous. 



Faujasia, D'Orbigng. Upper Cretaceous. 



; CoNOCLYPUS, Agassts. Tertiary and Cretaceous. 



