SKA-URCHINS. 453 



CoNULorsis, gen. nov.* 



Tlie following is a brief diagnosis : — AniV)itns circular, or very 

 slightly elongiited posteriorly ; adapiciil sin-face conical, not very 

 elevated ; adoral sui'face fljit or slightly concave. Peristome 

 small, slightly excentric, surrounded by interradial " bourrelets." 

 T'eriproct marginivl or inframarginal, transversely expanded. 

 Ambulacra of simple primaries, large adorally ; pores almost sub- 

 petaloid adapicaJly. Interambulaciu multituberculate, tubercles 

 not in vertical series, deeply scrobiculate, imperforate. Granu- 

 lation coarse, closely packed. 



Genotype. C. roemeri d'Orbigny, sub Galerltes. 



Upper Cretaceous. 



This genus corresponds with the " Ech.inoconus''' of Desor (21), 

 but is certainly not a member of the Holectypoida. " Galerites 

 roemeri" is not a " Galerites" at all, but, like the '■'■ Echinoconus 

 ahhreviatus'' of our own uppermost Cretaceous (its probable con- 

 gener), seems to be a near ally of Caratomus (see Hchlueter, 54), 

 but to be sufficiently distinct to demand a new generic name. A 

 further discussion of the afKnities of Conulopsis will be found on 

 p. 491. 



Adelopxeustes Gauthier. 



This genus is founded on one specimen, A. laud>erti, from the 

 Upper Chalk of Tunis. It is compared by CJauthier (46) with 

 Galerites roemeri d'Orbigny, and the coiupaiison, jiulging by the 

 figures, seems justified. It must therefore follow Conulopsis to 

 the Caratomus-^voxx^. 



CONOCLYPEUS Agassiz. 



There are two noteworthy features which separate this genus 

 from the Holectypoida. There are no branchial incisions on the 

 margin of the peristome, and the andjulacra are definitely sub- 

 petaloid. Moreover, the interambulacral tubei'cles are closely 

 packed, without any recognizable vertical arrangement. Cono- 

 ch/peus, and with it probably Ovidypeus Dames, represents the 

 most primitive family of the Clypeastroida. The family name of 

 Conoclypeidfe used by Gregory (60) may be retained for these 

 two genera. 



Amblypygus Agassiz. 



This genus has not, so far as I am awai-e, been previously 

 associated with the Holectypoida, but its affinities with that order 

 ai-e at least as well marked as those of the genus last mentioned. 

 It is certainly edentulous, and the tubercles are quite irregularly 

 packed together on the interambulacra. The ambulacra, how- 

 ever, in spite of an appreciably subpetaloid development on the 



* A more detailed uccouiit of tlie cliaracters of this genus will be given in ;i j)ai)er 

 that I liopc to jjublish shortly. 



