PEOF. A. DENDY ON SPICULES OF CHIKODOTA GEMINIFEKA. 251 



Note on the Spicules o£ Chirodota geminifera, Dendy & Hindle. 

 By Prof. Arthuk Dendy, F.R.S., Sec.L.S. 



[Read 4tli June, 1908.] 



The species, Chirodota geminifera, was proposed in 1907 *, for a specimen 

 from New Zealand which had been collected in 1896 and had been preserved 

 for eleven years in alcohol. The supposed distinguishing features of the 

 species were the absence of " wheels " and the presence of sharply pointed 

 sigmoid spicules apparently arranged in pairs. I have now found that 

 the peculiar character of the sigmoid spicules is due to erosion. Experiments 

 with Chirodota dunedinensis show that when the integument is treated 

 for four or five minutes with 70 ^/o alcohol containing 5 % of hydrochloric 

 acid, the spicules are partially dissolved. The sigmata entirely change 

 their appearance. They become sharply pointed at each end and may even 

 appear double, resembling those figured by us for C. geminifera. 



Fortunately I have found an old microscopic preparation from the 

 type of C. geminifera, made while the specimen was still comparatively 

 fresh and showing the spicules in their natural condition. There are no 

 wheels, but the sigmata closely resemble those of C. dunedinensis, the 

 one end being sharply reflexed and sharp-pointed and the other spirally 

 incurved in a plane at right angles to the first. They are, however, 

 a good deal smaller than those of typical C. dunedinensis, measuring 

 only about 0*066 mm. from bend to bend as against O'll mm. 



I have lately received some specimens of Chirodota, from one of the 

 Islands lying to the south of New Zealand, whose spiculation is intermediate 

 in type between that of C. dunedinensis and that of C. geminifera, and 

 which lead me to conclude that the latter is closely related to the former. 

 This question, however, will be discussed in another place. 



* Journ. Linn. Soc, Zool. vol. xxx. p. 95. 



