Professor Herdman on the StrucUtre of Sarcodictyon. 33 



cruise among the Hebrides during August 1850 he dredged 

 Sarcodictyon catenata and also a second species, Sarcodictyon 

 agglomerata, " in 30 fathoms water ofi' Croulin Island, and 

 also between Easa and Scalpa." In this paper Sarcodictyon 

 agglomerata is described as a new species, and a brief 

 account is given of its external appearance, in which it is 

 stated that the colour is "invariably ochraceous yellow," 

 while " the polype cells, instead of being arranged in single 

 file, are grouped together in assemblages of from three to 

 five, each group being connected with its neighbours by a 

 stolon-like extension of the polypidom." 



In the previous summer, in his " Eeport on the Investiga- 

 tion of British Marine Zoology by means of the Dredge," 

 read before the British Association at Edinburgh,^ Forbes 

 had referred to the two species of Sarcodictyon as having 

 been found in the following localities : — S. catenata, in 1845, 

 off Armadale, Sound of Skye, IJ mile from shore, depth, 

 25 fathoms, bottom, mud and stones ; in 1845, at entrance 

 of Sound of Skye, J mile from shore, depth, 20 to 30 fathoms, 

 bottom, mud and stones; in 1850, in Arcs Bay, Sound of 

 Mull, 1 mile from shore, depth, 25 fathoms, bottom, stones 

 and sand; in 1850, off Croulin Island, J to 1 mile from 

 shore, depth, 25 fathoms, bottom, gravel; also in Clyde 

 district, depth, 20 fathoms, bottom, stones ; and in Hebrides, 

 depth, 15 to 20 fathoms, bottom, stones and shells. S. 

 agglomerata, in 1850, off Croulin Island, J mile from shore, 

 depth, 30 fathoms, bottom, stones and gravel. Hence 1845 

 appears to be the date of the discovery of Sarcodictyon 

 catenata. 



In the " Annals and Magazine of Natural History " for 

 1858,^ Mr P. H. Gosse has a paper " On Sarcodictyon catenata 

 (Forbes)," in which he gives an account of a small colony of 

 the species, which he found on the south coast of England, 

 and succeeded in keeping alive for some time in an aquarium. 

 Some points in his description will be referred to further on. 



In December 1867, Pourtales, in the " Contributions to the 



1 Brit. Assoc. Rep., 1850, p. 192, et seq. 

 Ann. and Mag. Nat. Hist., ser. 3, vol. ii., p. 276. 

 VOL. VIII. 



