SPONGIIDA. 
15 Spong, 
Geodia areolata, G. ramo-digitata, G. gloho-stellifera^ Carter, (1) pp. 133 
& 134, pi. vi. figs. 31 & 36-38, Gulf of Manaar. The last species has 
globo-stellate spicules mixed with the balls of the crust. 
Stellogeodia, Czerniavsky, (2) p. 280. A new subgenus of Geodia^ 
based on Geodia stellosa, sp. n., id. ihid.j Black Sea. This subgonus stands 
midway between Stelletta and the typical Geodue ; the cortex and outer 
membrane contain numerous small short-rayed stellate spicules ; the 
parenchyma contains numerous short-rayed stellates besides the balls. 
Isops, Sollas, (12) p. 396. Differs from Geodia, s. str., Cydonium, and 
Pacliymatisma, in having the incurrent and excurrent orifices si milar and 
placed at the ends of simple cylindrical tubes. I. phlegrcei, id. 1. c. p. 397, 
pi. xvii., Kors Fiord, Norway, 180 fath. Has a subcortical layer, fibrous 
externally, internally formed of gelatinous connective tissue, containing 
fusiform cells. The mark exhibits no cells, and therefore is a syncytium. 
Sheath of long spicules tri-laminar, consisting of fusiform cells, hyaline 
fibres, and in places gelatinous connective tissue. Development of globatc 
spicules traced from “Trichites.” “Chones” \infrd, p. 20] and canal- 
system described at length. Ciliated chambers occur on all the in- 
current canals. 
Stelletiinopsis annulata, Schmidt, (9) p. 75, pi. ix. fig. 6, habitat un- 
known, evastnim, id. ibid. p. 77, Grenada, 170 fath. 
Stelletta norinani, Sollas, (12) p. 132, pis. vi. & vii., Kors Fiord, Nor- 
way, 180 fath. A central mark-substance is distinguished from the 
cortical substance ; it consists of finely granular protoplasm, becoming 
striated towards the canals ; a muscular layer underlies the superficial 
spicular layers, and is lined internally by some largo cells, and by a 
nucleated epithelial membrane. The chone or intermarginal cavity is 
divided horizontally by a sphincter into an ectochone and endochone. 
The bundles of trichites are probably homologous with the globate-spicules 
of Geodia ; a nucleus lies at the end of each bundle. 
Stelletta tethyopsis, Carter, (1) p. 137, pi. vi. figs. 39 & 40, Gulf of 
Manaar. 
Stelletta carhonaria, Schmidt, Arch. mikr. Anat. xviii. p. 280, Gulf o| 
Naples. Spicules chiefly acerate and acuate ; also some scattered forked 
anchors, delicate stellates and spiral stellates. S. fihulifera, id. ibid., Gulf 
of Naples ; six kinds of spicules. 
Stelletta profunditatis, Schmidt, (9) p. 70, Gulf of Mexico, 1920 fath. 
S. pygmceorum, id. ibid. pi. ix. fig. 9, St. Vincent, West Indies, 95 fath. S. 
mantoidea, id. ibid. pi. x. fig. 1, Grenada, 262 fath. Many “ persons 
are united into one “ stock.’' 
Pachastrella lithistina, Schmidt, (9) p. 68, pi. ix. fig. 3, Gulf of Mexico 
or Caribbean Sea. Besides its stellates, it contains irregular tubercu- 
lated masses in its dermis. 
Corticium versatile, Schmidt, (9) p. 69, pi. ix. fig. 5, St. Vincent’s, West 
Indies, 95 fath. 
Plahina [P/ac-], F. E. Schulze, (11) p. 448. Growth sessile, encrusting ; 
surface bearing one or more projecting oscular tubes ; besides the three 
forms of spicules distributed irregularly over the tissues, there is a single 
peripheral layer of candelabrum-like quadri-radiates, whoso chief rays 
