ATI. ANT. DEEP-SEA EXPED. 1910. VOL. III]. 



SPONQIA. 



15 



Locality: Between Gibraltar and Gran Canaria, lat. 

 35° 32' N, long 7" 7 W, 1215 metres, and lat. 35" 

 34' N, long 7° 35' W, 1615 metres. Bottom in both 

 places yellow mud. 



Petrosia friabilis Topsent. 



PI. Ill fig. 5. 



Vide Litter: 24, p. 69. 



St. 23. One fragment. 



A mass 6.5 cm. X 3 cm. X 4.5 cm. of a rather 

 firm but friable consistency. Several circular, sharply 

 marked oscula with a diameter varying from 3 to 6 mm. 

 Colour in spirit dirty yellowish white. The sponge is 

 traversed by large canals. The dermal membrane is rather 

 thick and consists of a dense reticulation of oxea of the 

 same kind as in the choansome, but they are here irre- 

 gularly arranged. The shape of the oxea agrees well 

 with Topsent's figure (pi. X fig. 4, op. cit.) and with 

 his preparations, which I have had for comparison, but 

 the proportions are somewhat larger varying from 0.333 

 —0.444 mm. in length and being about 0.015 mm. thick. 



Geographical distribution. The species has been 

 recorded from the Azores (130 — 927 m.) and from the 

 southern entrance of the Bay of Biscay (134 — 300 m.) 

 (op. cit. p. 69) where it is, according to Topsent, a very 

 common species. 



The locality of. the „Michael Sars" specimen is 

 the Spanish Bay (35" 32' N, 7'" 7' W), 1215 m. 



Temperature 10.17" c. (at 1200 m.). 



Chondroc/adia Michaelsarsii sp. n. 



St. 23. One specimen and fragments. 



St. 35. One specimen and fragments. 



St. 41. Several fragments. 



The general appearance of the "Michael Sars" speci- 

 mens recalls Oscar Schmidt's figures of Chondrocladia 

 conrescens O., Schmidt (25, Taf. X, fig. 89) and Fristedt's 

 figure (9, pi. 31, fig. 26) of Cladorhiza nobilis Frist., found 

 by Lundbeck to be synonymous with Chondrocladia 

 gigantea Arm. Hansen (17). 



With Lundbeck's own figure (17, pi. IV, fig. 1) of 

 Ch. gigantea Arm. Hansen it shows on the contrary less 

 resemblance. 



Only two specimens are tolerably well preserved, one 

 from station 23 and one from station 35. 



The specimen from station 23 has a body 32 cm. in 

 length (-j- 7 cm. for the stalk and root) and that from 

 station 35 is 50 cm. in length (-f 1 cm. for the stalk 

 and root). The stalk is in both nearly uniform in thick- 

 ness throughout the whole length: in the larger specimen 

 1 — 2 cm. and in the smaller one 0.5 — 0.7 cm. 



The stem has whorls of irregularly clubshaped bran- 

 ches, about 2 cm. long, set with small globular swellings. 

 Ordinarily there are four branches in each whorl. The 

 branches coalesce with each other and the neighbouhring 

 stems seem to do the same, as sometimes two stems form 

 a cross. One of the specimens is forked at the upper 

 end, while the other is undevided and tapering somewhat 

 towards the apex. The surface is minutely hispid, with 

 either irregular, circular or oval apertures here and there. 

 The further anatomical structure corresponds in all essen- 

 tials with Lundbeck's description of Chondrocladia 

 gigantea Arm. Hansen (17, p. 104). Thus there is a crusty 

 layer, easily peeled off, while the dermal membrane proper 

 is difficult to detach. Further there is a copious system 

 of subdermal cavities and canals (where generally anne- 

 lids have taken shelter). A rope-like, twisted skeletal axis 

 runs throughout the sponge and diverges into the bran- 

 ches. In the stalk — which is rather muddy there is no 

 lacunous layer between the coating and the axis. 



Spiculation. The megasclera are smooth styli: 

 In the axis they are from 1.7 mm. to 3.4 mm. in length, 

 or even longer, and generally about 0.056 mm. in thick- 

 ness, while in the other parts of the body they obtain 

 only a length of about 1.2 -1.7 mm. with a thickness 

 of 0.011 — 0.030 mm., but there is no distinct separation 

 between them. Thus they are somewhat longer than in 

 Ch. gigantea (1.2—2 mm. and 0.56 — 1.2 mm.) and 

 aproach those in Ch. concrescens Ridley and Dendy 

 (4.5 mm).; in shape, they are more like those in the for- 

 mer, perhaps not so suddenly tapering at the upper end. 

 Besides the smooth styli there are in the stalk-coating 

 finely granular styli, generally 0.37 mm. long and 

 0.007 mm. thick, thus also somewhat larger than in 

 gigantea (0.118 — 0.340 mm.) but otherwise resembling 

 them (pi. XIII, fig. 2 c). The microsclera are isanchorae 

 unguiferae of the typical chondrocladia-shape, generally 

 with 7 teeth, but sometimes having 6 or 8, and all of 

 one size, about 0.099 mm. — thus agreeing with the "Chal- 

 lenger"-forms. Plenty of sigmata with compressed ends, 

 0.037 — 0.063 mm., have been observed in all parts of 

 the sponge, though most abundantly in the branches. 



As will be seen from the above description the 

 Chondrocladia obtained by the "Michael Sars" can not 

 easily be identified with any one of the species in question: 

 Ch. gigantea Arm. Hansen, Ch. concrescens O. Schmidt 

 and Ch. concrescens Ridley and Dendy. — Lundbeck 

 thincks the Ch. concrescens of Schmidt and that of 

 Ridley and Dendy are two different species, and he is 

 certainly right I believe.— Our form has affinities with 

 each of the three, thus in the abcenee of small anchorae 

 and in the proportions of the large it corresponds with 

 Ridley and Dendy's concrescens, whilst in general ana- 



