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



such forms as those of Hemiaster gibhosus here figured and those of the ordinary Dosmo- 

 sticha consisting of a simple tube with a terminal sucker (see Eevis. Echini., pi. xxxi. 

 figs. 4-9). 



Station 191. September 23, 1874. Lat. 5° 41' S., long. 134° 4' E. ; 800 fathoms ; 

 bottom temperature, 3 "9^ C. ; mud. 



Station 232. May 12, 1875. Lat. 35' 11' N., long. 139° 28' E. ; 345 fathoms; 

 bottom temperature, 5"0° C. ; sandy mud. 



^Hemiaster zonatus (PI. XX. figs. 1-4). 



Hemiaster zonaius, Agassiz, 1879, Proc. Am. Acad., vol. xiv. p. 212. 



Loven has figured in his Etudes sur les Echinoidees, pi. xi. figs. 93, 94, a young 

 Hemiastei- [H. expergitus) collected by the "Eugenia" near the Azores at a depth 

 of 600 fathoms. The Challenger also dredged near the same locality specimens of a 

 Hemiaster which I cannot refer to Loven's species at present, although the difterences 

 between them are such that they may only lie due to age. 



This species difl'ers from Hemiaster gibhosus in having a deeper anal groove, a broader 

 and more eliptical peripetalous fasciole, and coarser spines more evenly distributed over 

 the whole of the abactiual surface. 



The outline of this species is also more globular, and it evidently has its nearest ally 

 in the characteristic Cretaceous Hemiaster prunella. 



Station 126. September 12, 1873. Lat. 10° 46' S., long. 36° 8' W. ; 750 fathoms; 

 mud. 



Station 8. February 12, 1873. Ofi' Gomera, Canaries ; 620 fathoms ; sandy mud and 

 shells. 



Rhinohrissus (Hemiaster) . 

 Rliinohrissus, A. Agassiz, 1872, Bull. Mus. Comp. Zool., vol. iii. 



* Rhinohrissus hemiasteroides (PI. XXXV.'' figs. 12-15). 



RJdnobrissus hemiasteroides, A. Agassiz, 1879, Proc. Am. Acad., voL xiv. p. 211. 



We find in this species a combination of some of tlie features of Rhinohrissus with 

 characters of Metalia, BrissojJsis, Hemiaster, and Brissus. It has the peripetalous fasciole 

 of the former, and the anal fasciole of the latter genera, the deeply sunken petals of 

 Hemiaster combined with the flush odd anterior ambulacrum and the remarkably broad 

 actinal ambulacral areas round the actinostome of Rhinohrissus. 



At first glance when covered with spines, this species would readily be taken for a 

 young specimen of Metalia sternalis, but it has, unlike this species, no anterior ambulacral 

 groove. The anterior ambulacrum is flush with the test which forms a slight keel in the 

 median anterior ambulacral area (PL XXXV. ^ figs. 12, 13). The peripetalous fasciole is 



