REPOKT ON THE TETEACTINELLIDA. 
221 
Cydonium magellani, Sollas (PI. XXL figs. 1-14). 
Cydonium magellani, SoUas, Prelim. Account, Sci. Proc. Eoy. Dubl. Soc., vol. v. p. 197, 1886. 
S'ponge (PI. XXL fig. l). — Large, turnip-shaped, or depressed cake-like; attached. 
Oscules not distinguishable from the pores, both forming the cribriform roof of chones. 
The spherasters of the outer layer of the cortex all of one kind. The spicules of the 
radiating sheaves, including oxeas, dichotrisenes and anatrisenes, pass through the cortex 
and project beyond it, rendering the surface hispid. 
Spicules. — I. Megascleres. 1. Oxea (PI. XXL fig. 2), fusiform, usually curved, 
bluntly pointed; from 3'927 by 0‘0516 mm. to 5’71 by 0’058 mm. 
2. Dichotiisene (PI. XXL figs. 3, 4), rhabdome conical, much attenuated proxi- 
mally, but rounded off at the end ; protocladi projecting outwards and forwards ; deutero- 
cladi sometimes horizontal, sometimes projecting forwards as well as outwards. Rhab- 
dome from 3‘927 by 0'064 to 4'82 by 0'09 mm., protocladi 0T27, deuterocladi 0'275 mm. 
long. 
3. Anatrisene (PI. XXL fig. 5), rhabdome cylindrical, rounded off proximally; cladi 
diverging differently in different varieties, sometimes curving outwards and backwards 
gradually, and then not markedly stouter near their origin ; sometimes rapidly bent 
backwards after curving more outwards than backwards, and then much thickened near 
their origin. Rhabdome 7T4 to 7'5 by 0'019 to 0'0237 mm., cladi from OTl to 0T6 mm. 
long, chord from 0T6 to 0T75 mm., sagitta 0103 to 0119 mm. 
II. Microscleres. 4. Sterraster (PI. XXL fig. 6), spherical, somewhat depressed ; 0123 
by 0103 mm. 
5. Somal strongylate spheraster (PL XXL fig. 7), a comparatively large centrum, 
with numerous short strongylate or abruptly truncate actines ; 0‘012 mm. in diameter. 
6. Subcortical oxeate spheraster (similar to that of Cydonium hirsutus, PI. XXL 
fig. 41), centrum 0'008 mm. in diameter, produced into conical oxeate actines, sparsely 
spined ; total diameter 0’0217 mm. This is confined to the neighbourhood of the 
subcortical crypts, occurring chiefly in the innermost fibrous layer of the cortex. 
7. Choanosomal oxyaster. — In the choanosome the strongylate spheraster (5) passes 
into an oxeate spheraster (PI. XXL fig. 8), and this into an oxyaster O'OIG mm. in 
diameter. 
Colour . — A warm brownish-white. 
Habitat . — Station 308, off Tom Bay, Patagonia, January 5, 1876 ; lat. 50° 8' 30" S., 
long. 74° 41' 0" W.; depth, 175 fathoms ; bottom, blue mud. 
Station 311, off Port Churruca, Patagonia, January 11, 1876 ; lat. 52° 45' 30" S., 
long. 73° 46' 0" W.; depth, 246 fathoms ; bottom, blue mud ; bottom temperature, 46°. 
Remarks. — Several specimens of this species were trawled. The largest, nearly perfect, 
is that figured; it measures 90 mm. in height and 100 mm. in diameter ; near the summit 
