340 THE VOYAGE OF H.M.S. CHALLENGEE. 



fourth radial is sometimes a syzygy. The rays generally divide four and sometimes five 

 times ; and their subdivisions are equal in value or nearly so. The first joint after each 

 axillary bears a pinnule, and the third is usually a syzygy. 



The terminal parts of the arms have a lai'ge number of undeveloped pinnules. Those 

 on the lowest parts of the rays have large, thick joints, the basal ones cuboidal and the 

 rest oblong. Those borne by the radials and lower distichals receive their ambulacra 

 direct from the peristome, or from the primary ambulacra of the disk. 



Remarks. — The name Metacrinus for this very w^ell characterised genus originated 

 with Sir Wyville Thomson ; but he drew up no diagnosis of it. Indeed it was only by 

 finding the name in his handwriting upon a proof of PI. XLVII. that I was informed of his 

 recognition of the type as distinct from Pentacrimis, under which name it had been 

 mentioned in the Station Book, and in various publications that dealt with the work of 

 the Challenger in the Pacific. I had known of the existence of a second livino; eenus 

 of Pentacrinidse for some months before the Challenger and "Blake" Crinoids came into 

 my hands. For my friend Mr. Charles Stewart, F.L.S., the present Curator of the 

 Hunterian Museum at the Eoyal College of Surgeons, had shown me early in 1881 a very 

 fine dry specimen which had been obtained in the neighbourhood of Singapore by one of 

 the ships belonging to the Eastern Telegraph Company. It was accompanied by a stem- 

 fragment of another species which I now know to belong to the same genus. Thanks to 

 his kindness, I have been able to describe them recently,^ together with yet another 

 species which had been dredged in the Japanese Seas by Dr. Doderlein, the Conservator 

 of the Natural History Museum at Strassburg, who courteously placed it in my hands for 

 this purpose. Eleven species were dredged by the Challenger, and there is another 

 which I have not examined personally. It was dredged by the famous " Vega " in 

 Yeddo Bay, during her stay in Japan in October 1879; but no description of it has 

 yet been published. It is at present in the hands of Prof. S, Loveu of Stockholm ; 

 and with his characteristic kindness he not only sent me some fragments of the stem, 

 but also allowed Mr. Percy Sladen, who was examining the Starfish collection in the 

 Stockholm Museum, to draw up a description of it for me. So carefully was this done, 

 that I have been enabled to recognise the afijnities of the type, and to assign it a 

 place in the classification of the genus which appears on p. 344. 



Both the calyx and the stem of Metacrinus, but especially the former, present very 

 striking diS"erences from the corresponding parts in Pentacrinus. In the latter genus 

 it is quite the exception for the number of radials to exceed three, which is so constant in 

 Ainocrinus, Millericrinus, Encrinus, and Comatula; and even when there are more, 

 none of them bear any pinnules. Thus there is no pinnule on the third joint of the 

 abnormal ray of Pentacrinus mulleri represented on PI. XV. fig. 2, in which the axillary 

 is the fourth joint above the basals ; nor on any of the five joints below the radial axillary 



■ On Three New Species of Metacrinus, Trans. Linn. Soc. Land. (Zool.), ser. 2, vol. ii. pp. 435-447, pis. l.-lii. 



