1906] The Species of Botrvocrinus. 97 



australian species. 

 Botryocrinus longibrachiatus. 



Botryocrinuslongibrachiatus, F. Chapman, 1903, Proc. R. Soc. Victoria 

 (n.s.) XV, p. 108. 



Dorsal cup conical, with straight sides, the plates slightly 

 rounded, RR projecting very slightly if at all. Height (7.2 mm), 

 100 ; width at base, 44 ; width at summit, 125. IBB and BB 

 slightly higher than wide. RR about as high as wide. Arm-facet 

 not more than .5 of R. x rather wide and apparently supporting 

 3 tube plates. Proximal columnal quinquelobate. 



Silurian, Brunswick, Victoria. 



Three cotypes in National Museum, Melbourne, No. 390 392 

 Of these, No. 390, shown in Chapman's pi. xviii, f. 6, should be 

 taken as lectotype. Plastotype in British Museum, No. E7130. 



The present diagnosis differs in some respects from the 

 account given by Mr. Chapman, being based on the excellent wax 

 squeeze which he so kindly sent. From this it appears that the 

 plates were somewhat disarranged, and that the specimen was flat- 

 tened, thus appearing wider above than it really was. Mr. 

 Chapman only measured to half-millimetres, but measurement 

 with sliding callipers and a vernier gives : Height, 7.2 mm.; 

 width at base, 3.2 mm.; width at summit, 10 mm. In calculating 

 the proportions for the diagnosis I have reduced the last measure- 

 ment to 9 mm. ; it may have been even less. Thus the propor- 

 tions and form of the cup do not so closely resemble B. qiiLnque- 

 lobus as would appear from the published figures. It was, Mr. 

 Chapman has informed me, mainly this supposed resemblance 

 which led him to refer the species to Botryocrinus notvvithstanding 

 the apparent invisibility in both species of structures definitely 

 diagnostic of the genus. Examination of the wax squeeze, how- 

 ever, convinces me that those structures are after all to be seen in 

 B. longibrachiatus. Chapman's pi. xviii, f. 6, is in fact viewed 

 from the left posterior radius, 1. post. R being the middle of the 

 three plates in the uppermost circlet, the plate on its right hand 

 being x, the plate below it on the right being post. B., and the small 

 plate, of which a portion is seen to the right between post. B and 

 x, being RA. The edge of r. post. R is seen to the right of x. 



