GENERA, SPECIES, &C. 
Spong . 13 
■which the often very extensive cavities are occupied by its substance, 
and from the inadequacy of the theory of erosion by Annelids to account 
for the appearances. The latter point is enforced by the absence of any 
traces of Annelids in the cavities, by the fact of the burrow increasing 
in diameter inwards, and by its notched and not smooth contour. 
Cliona caribbcea, Carter, (2) p. 346, pi. xii. fig. 26, St. Vincent, W. Indies. 
Vioa johnsioni , Schmidt : the species thus named in 1862 is renamed 
V. schmidti ; id. (2) p. 348. 
Spongia dysoni, id. (2) p. 350, pi. xii. fig. 25. 
Alcyonium [= Spirastrella , Rec.] purpureum , Lamarck ; id. (2) p. 352, 
pi. xii. fig. 28. 
Terpius fug ax, Duchassaing de Fonbrcssin & Michellotti, re-identified 
and described ; id. (2) p. 355, pi. xii. fig 29, as a Suberitid. 
Thecophora semisuberites, Schmidt ; Vosmaer, (17) p. 30, pi. iv. figs. 
133-136. 
Polymastia mamillaris, Bowerbank, Suberites append iculatus, Balsamo- 
Crivelli, Rinalda arctica , Mereschkowsky, all united with Spongia peni- 
cillus, Montagu, as Polymastia penicillus , by Vosmaer, (17), described, 
p. 26, pis. i. figs. 12 & 13, iv. figs. 127-132, from the Barents Sea. 
Axos cliftoni, Carter, (2) p. 362. 
Xenospongia patelliformis , id. (2) p. 357, pi. xii. fig. 32. A Group, 
Xenospongina, proposed by Carter, to include this form. 
Rhizaxinella clavigera , Keller, = Alcyonium pyriforrne , Delle Chiaje, 
and Cribrella labiata, Keller, = Osculina polystomella, Schmidt, accord- 
ing to Vosmaer, (16). 
Tethya lyncurium , a new var., obtusum , described by Vosmaer, (17) p. 25, 
pi. iv. figs. 123-126, from near Hammerfest ; based on the short stout 
rays of the globostellate spicule. 
Donatia. A stellate spicule with spined arms, figured from a Cape of 
Good Hope specimen ; Carter, (2) p. 361, pi. xii. fig. 23. 
Donatia lyncurium , id. (2) pp. 358 & 360. Its distribution said to extend 
from Great Britain to W. Indies, the Cape, Mauritius, and S. Australia. 
Tetractinellida. 
Dercitus, Gray, upheld by Norman, (1) p. 93, as the true name of 
Battersbyia and Pachastrella ; list of described species given. 
Thenea wallichi. Under this name, Sollas (15) p. 427, pi. xvii., 
unites Wyvillethomsonia ( Thenea ) wallichi, Wright, Stelletta agarici- 
f or mis, Schmidt, Dorvillia and Tethya agariciformis, Kent, and distin- 
guishes the species from Tethya muricata, Bowerbank. The form and 
canal system, skeleton, and histology are fully described, and notes 
given on some of the developmental stages. Externally, it is remarkable 
for an annular depression, the equatorial recess, the chief seat of the 
pores. The pores communicate with ciliated chambers by series of 
'vesicles, representing inhalant canals, and shut off from each other by 
sphincters ; parts of the exhalant canals are also similarly vesicular. 
The probable explanation of these structural peculiarities is the need 
of a rapid, yet controllable, passage of water. Calculations are 
