256 TEiASSic CREsroiDS TROM :E^rEW ZEALA]S'D. [vol. Ixxiii, 



Apart from this peculiar character, the species differs from other 

 known Triassic species. Those which resemble it in the crenelation 

 of the sutm-e and in the absence of a radial triangle have petal- 

 floors depressed, and not flush as here. In I. trechmanni, which 

 has flush petal-floors, the peripheral crenellse are fewer and are 

 generally confluent. 



ISOCEl^^IJS GEATI?y^.^, sp. nov. (Fig. 15, p. 248.) 



Transverse section a slightly excavate star with rounded angles. 

 Normal joint-face with lumen small (obscure, saj^ 0*5 mm.) ; 

 central area merging into adradial crenellse; petals narrow (4*4 mm. 

 long, 1-6 mm. at greatest width, giving ratio of 0*36), their floors 

 depressed, with a greatest width approximately one -third of the 

 width of the petal (actually 0*6 mm.) ; adradial crenellse, after the- 

 obscurely formed adcentral crenellse, are about 10 on each side, 

 regularl}^ corresponding, 0"5 mm. long; peripheral crenellse estimated 

 at 5 (the ends of petals are broken) ; a well-marked radial triangle 

 with surface rising gently towards the radius in its outer (acentral) 

 region. 



Approximate measurements : — IE = 4'9 mm. ; r = 3'1 mm. ;. 

 reentrant angle = 0"7 mm. ; making diameter = 8*7 mm. 



Localit3^ — Cove 3 miles north of Dall Head, Gravina Island 

 (S.E. Alaska). 



Horizon. — Upper Trias, supposed to be Lower Noric (see- 

 a. C. Martin, 1916, p. 700). 



Material. — Squeezes in various substances from sjDecimens in 

 the collection of the U.S. Geological Survey, and plaster casts- 

 taken therefrom in the British Museum, Geological Department. 

 Eegistered E 21913, E 22181-22182. An obscure squeeze, 

 E 21914, indicates that a more broadh^ petaloid Isocrinus occurs 

 in the southern arm of this cove. 



Holotype. — Plaster cast, E 22181 and its original at 

 Washington. 



Relations. — A very distinct form. In the large radial triangle 

 and narrow petals it approaches a true Pentacrimis much more 

 closely than does Isocrinus argenfeiis, and, unlike that species, it 

 has no radial ridge-groups.] 



A radial triangle is slightly developed in Isocrinus 'projnnqiius 

 and is well marked in an undescribed Isocrinus in Dr. Wanner's 

 matei'ial from the Upper Trias of Timor. All these species are 

 thereby distinguished from I. treclimanni. 



There seems no doubt, then, as to the specific independence of 

 these New Zealand fragments, and I can find no name more fitting 

 to be associated with them than that of their collector, who has 

 thrown so much light on the real and alleged Triassic deposits of 

 New Zealand. 



[November 30th, 1918. 



