ECHINODEEM LAEV^. 5 



in the pre-oral pair ; for while these are mere rudiments in E. antarcticus, they are 

 almost equal to the length of the body in E. esculentus. 



The other two larvae, E. coronatus and E. theeli, were described by Mortensen (9). 

 The first of these is a larva of about the same or a slightly older stage than our 

 specimens. In it, however, the post-oral and postero-dorsal arms are about one and a 

 half times as long as the body, while the antero-laterals and pre-orals are equal to it 

 in length. Besides this great difference in the arms there is also a difference in the 

 posterior pair of epaulettes ; for Mortensen describes these as " very broad," while in 

 E. antarcticus they are much the smallest of the six. 



In E. theeli we are dealing with a larva which is much younger than the others 

 just mentioned, but even here we see certain features in the arms by which to 

 differentiate the two ; for while three pairs of the arms are of about the same 

 proportionate length as in our specimens of E. antarcticus, the fourth, the pre-orals, 

 are long and well-developed, not at all resembling the mere rudiments by which they 

 are represented in the latter species. 



As in the case of the Ophiopluteus, so here nothing can be made out of the 

 skeleton, the result, probably, of the method of preservation. 



On the left side of the larva a well-developed " Echinus-rudiment " can be seen, 

 but of this no details can be made out in either of the mounts. 



4. CUCUMARIA CROCEA. 



Eolothuria {Gucumaria) crocea, Lesson, Cent. Zool. (1832), p. 153, pi. lil., fig. 1. 

 Cucumaria crocea, Lampert, Seewalzen (1885), p. 214. 



Our collection contains some two hundred specimens of the young of this 

 Holothurian, "born after the capture of the mothers," and one adult female, the 

 parent of some of these young ; all taken at Hut Point, near the Winter Quarters of 

 the Expedition, on the 13th and 28th of February, 1904. 



The young of this species were first dredged by the ' Challenger ' at the Falklands 

 in January, 1876. Since that time nothing, so far as we can learn, has been added to 

 our knowledge of their development, and as the specimens then found were of a 

 considerably older stage than those brought back by the ' Discovery,' it may be well 

 to recall certain of the observations made by Sir Wyville Thomson at that time, which 

 have a special bearing upon the developmental history. 



In his " Voyage of the ' Challenger,' " Sir Wyville says : " In a very large 

 proportion of the females which I examined, young were closely packed in two 

 continuous fringes adhering to the water-vascular feet of the dorsal ambulacrum. 

 The young were in all the later stages of growth, and of all sizes, from 5 mm. up to 

 40 mm. in length ; but all the young attached to one female appeared to be of the 

 same age and size. ... All the young I examined were miniatures of their parents ; the 

 only marked difference was that iai the young the ambulacra of the bivium were quite 



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VOL. IV. 



