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



In Linopneustes the pedicellarise (PI. XLIII. figs. 6-8 ; PI. XLV. figs. 11-19) do not 

 greatly differ from the pedicellarige of Paleopneustes, and are remarkable for the great 

 size of the spaces left between the valves of the head. 



* Linopneustes murrayi (Pis. XXV., XXXV.^ figs. 8, 9 ; PI. XXXVIII. figs. 24, 28, 

 29 ; PI. XLIII. figs. 6, 8 ; PI. XLV. figs. 11-19). 



Paleopneustes Murrmji, A. Agassiz, 1879, Proc. Am. Acad., vol. xiv. p. 210. 



It was with considerable doubt that I referred this species to Paleopneustes. The 

 presence of a subanal fasciole and a peripetalous fasciole would at first seem to remove 

 it from Paleopneustes, with which it agrees in its general features, such as the structure of 

 the ambulacra! petals, of the actinostome, and of the actinal side of the test. The series 

 collected is composed mainly of large specimens varying in size from 80 mm. to 130 mm. ; 

 in some of them the subanal fasciole is most indistinct, consisting merely of an occasional 

 accumulation of miliary tubercles, and the same is the case with the peripetalous fasciole 

 which is in some cases interrupted by breaks, or so diffuse as to lose its distinctive 

 character as a fasciole. So much weight has been laid upon the presence or absence of 

 this fasciole especially in the fossil genera, which had been multijilied now to an extra- 

 ordinary degree, that a careful study with large material in all possiljle stages of growth of 

 some of the recent genera such as Plemiaster Shizaster, Faorina and Maretia would go 

 far to determine whether the presence or absence of fascioles really has the systematic value 

 attached to it. In the species of Hemiaster which I have had occasion to study, the 

 changes undergone by the fascioles during growth are remarkable and the variations in 

 the extent and importance of the fasciole extreme. See the descriptions of Hemiaster 

 cavernosus collected by the Challenger. 



From the specimens oi Paleopneustes proper collected by the " Blake" very great changes 

 in general appearance evidently take place during growth, and it may be that the frag- 

 ments of a species of Spatangoid which I regarded in the report on the " Blake" Expedi- 

 tion (Echini, Bull. Mus. Comp. Zool., 1878, vol. v. No. 9) as intermediate between 

 Eupatagus and Paleopneustes, may be perhaps only a species of Paleopneustes allied to 

 Linopneustes murrayi, having like it a very jirominent peripetalous fasciole more marked 

 even than in any specimen of that species I have had occasion to examine. I have called 

 attention to the unsatisfactory state of our knowledge of the value of fascioles while 

 speaking of some species of Maretia and of Lovenia, from which it would almost appear 

 as if disconnected lengths of fascioles might appear anywhere on the test provided the 

 miliaries of that portion of the test were sufficiently crowded together. 



A fragment of a large sjiecimen was obtained at Station 2 1 in which the peripetalous 

 fasciole is quite close to the ambitus, running immediately on the edge of the test, and in 

 which the anterior ambulacral groove is somewhat deeper than in the specimens from 

 Japan. Around this there are from three to four smaller lines of fascioles made by the 



