SIR C. WYVILLE THOMSON OK CERTAIN ECHIN0DEEMJ8. 55 



Hyocrinus hethellianus, sp. n. 



H. bethellianus ? 

 The last is a beautiful little thing which we dredged from a 

 depth of 2325 fathoms at Station 223, lat. 5° 31' N., long. 

 145° 13' E.,in the east Pacific, with a bottom of Glohigerina-ooze, 

 and a bottom-temperature of 1°"2 C. It certainly is in many re- 

 spects very unlike the adult IS. hethellianus ; but it may possibly turn 

 out to be the young of that species. There was only one specimen. 

 It has been found impossible, or at all events too dangerous, to 

 examine and compare the species belonging to the Pentacrinidse 

 on board ; many of the specimens are very large, and they are very 

 tender, requiring the utmost delicacy in handling ; it has there- 

 fore been thought in most cases advisable to pack them away in 

 safety at once, and to defer their discrimination until our return 

 home. 



' Challenger,' South Atlantic, . 



March 5th, 1876. 



Notice of some Peculiarities in the Mode of Propagation of certain 

 Echinoderms of the Southern Sea. By Sir C. Wtville 

 Thomson, LL.D., D.Sc, F.E.S., E.L.S., P.G.S., &c., Eegius 

 Professor of Natural History in the University of Edinburgh, 

 Director of the Civilian Scientific Staff of the * Challenger ' 

 Exploring Expedition. 



[Read June 1, 1876.] 



The very remarkable mode of reproduction of certain members of 

 all the recent classes of Echinodermata by the intervention of a 

 free-swimming bilaterally symmetrical " pseudembryo " developed 

 directly from the "morula," from which the true young is subse- 

 quently produced by a process of internal budding or rearrange- 

 ment, has long been weU known through the labours of a host of 

 observ^ers headed and represented by the late illustrious Professor 

 Johannes Miiller of Berlin. 



At the «ame time it has all along been fully recognized that re- 

 production through the medium of a " pseudembryo " is not the 

 only method observed in the class, but that in several of the Echi- 

 noderm orders, while in a certain species a wonderfully perfect and 

 independent bilateral locomotive zooid may be produced, in very 

 nearly allied species the young Echinoderm may be developed im- 



