123 THE VOYAGE OF H.M.S. CHALLENGER. 



ovarian pinnules of Antedon acoela and Antedon angustiealyx, and also in the substance 

 of tlie small later joints of the pinnules (PI. LIV. fig. 5). 



As regards the colouring matters in the body of a Crinoid I can do uo more than 

 refer to the important observations of Prof. Moseley, who employed the spectroscope on 

 five different occasions when Pentacrinidse were dredged in the Pacific (Stations 170, 192, 

 209, 210, 214). Metacrinus was obtained at all these Stations, but Pentacrinus only at 

 the first and the last two.^ 



The colouring matter yielded by most of the specimens is distinguished by very well- 

 defined absorption spectra, and has been termed " Pentacrinin " by Prof. Moseley. It is 

 freely soluble when fresh in slightly acidified alcohol, and gives a solution which is of an 

 intense pink when viewed by transmitted light, but acquires a bluish-green colour when 

 rendered alkaline by the addition of ammonia. " The fresh colouring matter is soluble in 

 fresh water, but remains partly suspended, forming a slightly opaque dark purple solution, 

 which gives, when quite fresh, a mixed acid and alkahne spectrum." All the species, 

 both of Metacrinus and Pentacrinus, which were obtained off the Kermadec Islands at 

 Station 170 were of a uniform dusky colour when fresh, being evidently coloured by acid 

 pentacrinin. The three species of Metacrinus dredged off the Ki Islands at Station 192 

 " when in the fresh condition, had their stems almost white, and their crowns of a light 

 yellow or fight reddish -orange, showing no purple coloration at all ; and those dredged 

 offthePanglao and Signij or Islands (Station 210) were almost colourless; nevertheless, 

 when placed in alcohol, they yielded a solution which was deeply coloured of a sap green, 

 and which when acidified, became of the usual deep pink of pentacrinin. The pentacrinin 

 was thus in these examples, though present in great adundance, entirely masked." 



I am unfortunately unable to name with certainty the species which was obtained at 

 Station 210, no specimens having reached me with the label of this Station; though, 

 according to Sir Wyville Thomson's MS. notes, four specimens of two species of Penta- 

 crinid^ were obtained here. One of these was perhaps the single individual of Metacrinus 

 murrayi, which reached me mthout any record of its locality ; while the other must 

 have been either Pentaci^inus alternicirrus or Pentacrinus naresianus. Three out of 

 seven individuals of the latter species came into my hands without any indication of 

 locality; whUe a few of the fourteen specimens of Pentacrinus alternicirrus were in the 

 same condition. Both were obtained at Station 214, off the Meangis Islands. 



There is, however, one difiiculty respecting the occurrence of Pentacrinus naresianus 

 at Station 210. For whde the individuals of this species dredged at Stations 170 and 

 214 had the dusky purple colour of acid pentacrinin, those supposed to have been 

 obtained at Station 210 were almost colourless, and the pentacrinin, though present, 

 entirely masked. 



1 On tlie Colouring Matters of various Animals, and especially of Deep-sea Forms diedged by H.M.S. Challenger, 

 Quart. Journ. Micr. Set. 1877, vol. xvii., N. S., pp. 5-10. 



