112 PROF. A. DENDY AND MB. E. HINDLE : ADDITIONS TO 



three spicules wide), one on either side o£ each mid-radial line, and thus in 

 the middle of the broad band o£ larger curved rods. 



The two ventral muscle-bands are much closer together than the other 

 three bands. 



The calcareous ring (fig. 9) is composed of twelve short nodular pieces, five 

 being radial and seven inter-radial in position (as in Chirodota fernandensis). 

 The two extra inter-radial pieces are situated one in each lateral dorsal inter- 

 radius. The inter-radial nodules possess two short posterior processes where 

 they join the radials. The latter are simple ovoid pieces. The figure shows 

 the junction o£ two inter-radials as well as that of the radials with the inter- 

 radials. 



The water-vascular system consists of an ambulacral ring, from which are 

 given off twelve large tentacular canals running up to the tentacles. A large 

 number of Polian vesicles arise from the ventral half of the ring (fig. 10). 

 In our specimen there are nineteen well-defined vesicles (/:».), and in 

 addition two or three papillas which may be small ones, but the number is 

 probably indefinite. A tightly-coiled madreporic canal (m.) runs forward in 

 the dorsal mesentery and ends in an oval madreporite. 



The gonads consist of two bunches of long cseca, extending to the middle of 

 the body, which are arranged right and left of the dorsal mesentery. From 

 their point of union, at about the level of the calcareous ring, the genital 

 duct runs forward in the dorsal mesentery. 



The characters detailed above, especially the size and the spiculation, 

 distinctly mark off this animal from all hitherto described species of Chirodota. 

 It is distinguished from C. dunedinensis, the only other known New Zealand 

 species with wheels, by 



(1) The much larger size of the animal. 



(2) The presence of twelve instead of ten tentacles. 



(3) The structure of the calcareous ring. 



(4) The presence of numerous Polian vesicles. 



(5) The absence of sigmoid spicules. 



(6) The presence of definitely arranged rods and granules. 



(7) The much smaller size of the wheels and the closure of the round 



holes on their outer faces. 



The species presents a condition intermediate between that of Chirodota, 

 in which the wheels are all aggregated into papillae, and that of Trochodota, 

 in which they are scattered. We therefore consider it undesirable to recognize 

 any generic distinction between these two forms. 



Chirodota geminifera, sp. n. (Plate 14. fig. 30.) 



We propose this name for a single specimen of a remarkable Chirodota 

 which was obtained from the New Brighton Beach, near Christchurch, by 



