198 THE VOYAGE OF H.M.S. CHALLENGER. 
This specimen was subsequently entrusted by Sir Rawson Rawson to Sir Wyville 
Thomson, together with two others which he had obtained in 1876, after the publication of 
Pourtalés’ notice of the first one. Sir Wyville described the three as follows :* “One 
is very complete in all important points, wanting only the two ‘bivial’ arms, but retain- 
ing the mouth-valves. The second is a little larger; it wants the mouth-valves, and 
again the bivial arms; and with Sir Rawson Rawson’s sanction I boiled this specimen 
down to figure and describe the separate parts. The third specimen is quite perfect, 
the arms closely curled in in their normal position when contracted; but it is very young, 
only about 8 mm. in height. Besides the four examples mentioned, I am aware of only 
another which I have not yet seen; it was shown at the Philadelphia Exhibition, and 
was afterwards bought by the Museum of Comparative Zoology at Cambridge, Mass.” 
The second of these seems to have been the original specimen described by Pourtales, 
from which the oral plates or mouth-valves had dropped away; and as it was gradually 
fallmg to pieces from natural decay, Sir Rawson Rawson allowed it to be dissected. 
The figures on Pl. III., with the exception of fig. 2, and figs. 1-4 on Pl. V., show the 
results of this process, Fig. 2 on Pl. II. is a slightly idealised view of the interior of 
the cup, so as to show the oral plates of the large specimen represented in Pl. II.’ This 
was supposed by Mr. Murray to belong to Sir Rawson Rawson, and as it corresponds 
to No. 1 of Sir Wyville’s list, I quite imagined this to be the case; but Sir Rawson 
Rawson does not recognise it as his, and I conclude therefore that it is the mutilated 
dry specimen which Prof. Agassiz informs me was sent by him to Sir Wyville with 
permission to ‘cut it up for details. In like manner Sir Rawson Rawson thinks it 
possible that the original of Pl. IV. may be his young specimen mentioned by Sir 
Wyville as only about 8 mm. in height, but as Prof. Agassiz tells me that he also sent 
Sir Wyville a small individual, I fear that two specimens have somehow been mislaid. 
The one which was shown at the Philadelphia Exhibition, and subsequently bought by 
the Museum of Comparative Zodlogy, is the original of Pl. I. 
It was obtained by Mr. Wilderboer, the collector for Sir Rawson Rawson, after the 
latter gentleman had left Barbados, and having come into the hands of Prof. Agassiz, 
it was sent by him to Sir Wyville Thomson, together with the Holopus material obtained 
during the dredging expeditions of the “Blake.” This consisted of (1) the very young 
individual shown in Pl. V. figs. 9, 10; Cruise of 1877-78; Station 22, 100 fathoms ; 
off Bahia Honda, lat. 23° 1’ N., long. 83° 14’ W.; temperature 71° F. (2) The single 
ray shown in Pl. Vb. fig. 4. This was preserved in spirit, and the greater part of it 
was subsequently cut into sections. Cruise of 1878-79; Station 157, off Montserrat, 
120 fathoms. 
1 On the Structure and Relations of the genus Holopus, Proc. Roy. Soc. Edin., 1877, p. 407. 
2 I did not find this out until too late to alter the notice of the oral plates of Holopus, which appears on p. 95. 
See p. 208. 
Ges | 
