TETRAXONTDA. 



49 



arose ; lastly, between these two, is a small raised knob with a rounded orifice on one 

 side of it. The narrow oscular canal is not central, but along one side of the thick 

 walled complete fistula. 



The second specimen is tubular, with a slightly enlarged solid base, whence arises 

 a fistula; the total length is 2'2 cm., and diameter '6 crn. No pores are discernible; 

 the subdermal spaces are about 2 mm. in depth. 



The eurypylous flagellated chambers are 23 p. in diameter. Cellules spheruleuses, 

 8-9 p. in diameter, are common. 



There is no bast-like subdermal layer as in Occanapia mollis Deudy (4. p. 248), 

 and the spicules of the latter are smaller, the oxeas being 200 x 8 p., and the sigmata 

 only 1C p.. Lundbeck (12. pp. 64, 6G) describes two species of GMus with fistulae, 

 and with a well-developed dermal bark, viz. : G. luridus and G. microtoxa, but both 

 these species have toxa in addition to sigmata. 



The two specimens were dredged off Hut Point (Winter Quarters) in 25-30 fms. 



GELLITJS GLACIALIS, var. nivea. 



(Plate XVII., fig. 4.) 

 1887. Gellius rjlacialls var. nivea Ridley and Dcndy (15. p. 42, PI. VIII., fig. 8, etc.). 



The one example is in the form of a small spherical knob attached to a branched 

 Polyzoon, resembling in these respects the ' Challenger ' specimen from Prince Edward 

 Island. The sponge, which is 17 mm. iu diameter, is brittle, and has a well-marked 

 ectosomal skeleton formed of tangential oxeas. The megasclerea and sigmata are 

 smaller than those of the ' Challenger ' specimen, but are in other respects of 

 the same character ; accordingly I have not regarded the Antarctic specimen as a 

 new variety. 



The larger sigmata are often united in bundles of sigmadragmata. 



The following table gives the dimensions in M of the spicules of G. glacialie, and 

 of the ' Challenger ' and Antarctic specimens of var. nivea. 



Dredged off Coulman Island. 100 fms. 



The 'Challenger' obtained G. t/lacialis from Agulhas Bank, 150 fms., and var. 

 nivea from Prince Edward Island, 140 fms. 



2 t; 2 



