NARRATIVE OF THE CRUISE. 379 



blowing a hard westerly gale, and it was a matter of congratulation that the ship had left 

 the insecure anchorage of Corinthian Bay. 



The necessity for leaving Heard Island without thoroughly exploring it was a source 

 of much regret. Had it remained fine for a few days, a survey might have been 

 completed which would have been all that was requisite for passing vessels, but the 

 unfavourable state of the weather prevented anything more being done than fixing the 

 position of its northern end, the remainder of the island being depicted from a sketch- 

 map made by the American sealing captains. The glaciers and peculiar formation of the 

 land, also, arc well worthy of investigation, more especially the sickle-shaped spit running 

 to the northward from its southeast extremity, from which shoal water is said to 

 extend. The report of this shoal water prevented the Expedition passing clown the east 

 side of the island, for it would have been dangerous for the ship to have become entangled 

 amongst shoals in the thick weather experienced, even had the wind been moderate. 



The deposit in 75 fathoms off Shag Island was a blackish green volcanic mud, 

 composed essentially of black volcanic sand and remains of organisms. There was ap- 

 parently not more than 1 or 2 per cent, of carbonate of lime, consisting of Miliola, 

 Discorbina, Uvigerina, and one or two Globigerina shells, along with fragments of 

 Polyzoa, Molluscs, Echinoderms, &c. The mineral particles had a mean diameter of 

 about O'G mm., and formed a black sand consisting chiefly of fragments of brown and 

 red glass— sometimes decomposed, sometimes massive and enclosing mieroliths of olivine, 

 and sometimes porous — with fragments of felspar, plagioclase. augite, and magnetite. 

 There were also very many Diatoms and Sponge spicules in the mud. 



The dredge brought up many specimens of Sponges, Alcyonarians, Holothurians, 

 Ophiurids, Eur yah, Asterids, Brisinga, Echinids, Annelids, Amphipods, Polyzoa, Gastero- 

 poda, Cephalopoda, and many other invertebrates resembling closely those obtained in 

 the dredgings around Kerguelen. 



Among the Echinoderms dredged at this Station was Psoitis ephippifer described by 

 the late Sir Wyville Thomson in the following interesting notes on the reproduction of 

 certain Echinoderms from the Southern Ocean : — " Adhering to the fronds of Macrocystis 

 there were great numbers of an elegant little cucumber-shaped Sea-slug (Cladodactyla 

 erocea, Lesson, sp.) from 80 to 100 mm. in length by 30 mm. in width at the widest 

 part, and of a bright saffron-yellow colour. The mouth and excretory opening arc 

 terminal ; ten long, delicate, branched oral tentacles, more resembling in form and attitude 

 those of Ocnvs than those of the typical Cucumariye, surround the mouth; the perisome 

 is thin and semitransparent, and the muscular bands, the radial vessels, and even the 

 internal viscera can be plainly seen through it. The three anterior ambulacra! vessels 

 are approximated, and on these the tentacular feet are numerous and well developed, 

 with a sucking-disk supported by a round cribriform calcareous plate, or more frequently 



