484 
. PROTOZOA. 
should, perhaps, be grouped together with Schmidt^s Chondrilla 
nucula, &c. ; hut the term Spharospongia should be suppressed. 
The spheroidal form is merely accidental in free specimens of 
Pachymatisma johnstonium and Tethya arabica ; and the fixed 
form is always encrusting, horizontal, and undulating. Their 
mode of growth is then fully described. The only true instance 
of a spheroidal sponge is seen in some specinjens of Tethya 
(Donatio) lyncurium and others, which grow on a pedicel. The 
habit of the species is then described, as the writer^s former 
figures and descriptions are inaccurate, having been made from 
dead specimens only. Two of the new species described, viz. 
Dercitus niger and Stelletta aspera^ possess a number of peculiar 
cells, similar to those of tfie GeodidcHy which appear to be repro- 
ductive agents (cf, M. Micr. J. v. pp. 185 & 186). 
Tethyidce. H. J, Carter reviews the confused synonymy of the group, and 
agrees with Gray in retaining Tethya^ Risso {=^Tetilla, Schmidt), for 2\ 
craniu7n and allies, and Donatia, Nardo, for T. lyncurium and allies. Ann. 
N. H. (4) viii. pp. 10^-105. 
II. J. Oarteb {1. c. vii. pp. 112-141, pis. 7-10) compares the fossil sponge- 
spicules of the greensand, which belonged almost exclusively to the Corallio- 
spongicc (including the EuplectellidcB) and the Pachtjtragi<By with those of ex- 
isting species. Carter suggests that the stem of Hyalonema may he the same 
as the beard of Holteniciy modified by the presence of a parasite. Parasitic 
polypi occur on other halichondroid sponges besides Hyalonema. Stelletta 
(Tisiphonia) agariciformis (= Wyvilletho^nsonia ivallicki, Wright) Tethya 
muricatay Bowerh., according to J. E. Gray. The deep-sea sponges and Co- 
ralliospongice occasionally mingle, and Stelletta aga7‘icifomm occurs both at 
178 and 1013 fathoms. 
Dorvillia agai'icifrnnisy Kent, ?= Tisiphonia agariciformis, Wyy. -Thoms. 
MS. ; and Wyvillethomsoiiia wallichi is probably its young form. None 
of the sexradiate forms, in addition to figs. 12 & 14, Kent, M. Micr. J. iv. 
pi. 66, are referable to Dorvillia, but have simply become entangled with 
the specimen by contact with examples of other species. Kent, Ann. N. H. 
(4) vii.pp.37&38. 
Dorvillia agariciformis figured by A. Cubitt, M. Micr. J. v. pi. 82, upper 
‘figs. 
JEhiplectella aspergillum described and figured by N. Funck, Pub. Inst. 
Luxemb. x. pp. 266 & 267, plate. 
Duplectella speciosa figured by M. Ponton, ‘ The Beginning, its When and 
its How,’ pi. N. 
Hyalonema sieboldi and EuplecieUa asperyilhwi, cf. E. Grube, JB. schles. 
Ges. xlvii. pp. 45-48. 
lanthella. Gray. W. Fleming (Verb. Ges. Wiirz. n. s. ii. pp. 1-7, pi. 1) de- 
scribes the structure of I. basta and I. Jlabelliformis very fully, and figures 
the former. (Spongia basta, Esp., does not belong to this genus at all.) The 
position of the genus lanthella is quite uncertain. Abstract, Z. ges. Naturw. 
(2)iv. PP.206&207. 
Cmdospongia, m g. W. S. Kent, P. Z. S. 1871, p. 616, Sponge consisting 
