170 THE VOYAGE OF H.M.S. CHALLENGER. 



Bowerbank's original diagnosis is, as usual, based entirely on the arrangement of the 

 skeleton. It is unnecessary to quote it at length {vide loc. cit.). The type of the genus 

 is Phakellia ventilahi-um, Johnston, sp. 



We have thought it desirable in this case to make use of external form as a eeneric 

 character, otherwise we know of no character which would serve to separate the genus 

 Phakellia from the genus Axinella. 



Phakellia ventilahrurn, Johnston, sp., var. connexiva, nov. (PI. XXXV. figs. 3, 3a). 



1842. Halicliondria ventUabrum, Johnston, British Sponges, p. 107. ^ 



1864. Phakellia ventUabrum, Bowerbank, Men. Brit. Spong., vol. i. p. 186 ; voL ii. p. 122, 



vol. iii. pi. xxii. figs. 1-7. 

 1866. PhaA-ellia rohusta, Bowerbank, Mon. Brit. Spong., vol. ii. p. 120; vol. iii. p. 54. pi. xxi. 



figs. 13-17. 



There are from Station 122 a number of fine, froudose specimens which we propose to 

 consider as a variety of the above species. In external form they are distinguished from 

 the tyi^es of the species by their greater size, altogether more robust growth and strong- 

 venation. The specimens are in the form of broad, flattened, erect lamella (PI. XXXV. 

 fig. 3), reaching as much as 200 mm. in height, with very strong, projecting veins 

 caused by the presence of stout bands of spiculo-fibre ramifying and anastomosing from 

 the base upwards. The surface is strongly hispid and in spirit the specimens are of a 

 brownish-yellow colour, in part due to the presence of a considerable amount of sand 

 adhering to them. 



The spiculation consists of smooth styli and stout "vermicular" spicules, the former 

 measuring about 1-5 to TS by 0'034 to 0-04 mm., and the latter about 0-65 to 072 by 

 0"035 mm. In spiculation the species Phakellia ventUabrum is practically identical with 

 Axinella erecta, but is separated from the latter by the very different external form ; 

 we also agree with Schmidt '^ in considering Bowerbank's Phakellia rohusta merel}- 

 as a variety of Phakellia ventilahrurn} 



Localities.— ^t&tion 122c, September 10, 1873; lat. 9" 10' S., long. 34° 49' W.; east 

 of Brazil ; depth, 400 fathoms ; bottom, red mud. A number of large pieces. 



Station 317, February 8, 1876 ; lat. 48° 37' S., long. 55° 17' W.; north-east of the 

 Falkland Islands ; depth, 1035 fathoms ; bottom, hard ground (gravel) ; bottom 

 temperature, 35° '7. One piece, of much more delicate appearance than the foregoing ; 

 almost white, and translucent, a condition which is, however, largely due to maceration, 

 probably owing to the time occupied in raising the specimen from such a depth. 



Hahitat. — British seas (Bowerbank, Johnston, &c.) ; Ireland (Johnston); Shetlands 

 (Bowerbank) ; between Scotland and Faroe Islands (Carter) ; south-west coast of 



' See also Johnston, loc. cit., for list of synonyms previous to his time. 



- Spong. Atlant. Gebiet., p. 62. 



' Details as to the minute anatomy of Phakellia ventilahrum, var. connexiva, will be found in the Introduction. 



