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



of those of Errina labiata (PL IY.) ; in order to accommodate their length within the 

 ampulla?. 



The male stocks of Pliobothrus symmetricus are in every way similar in structure to 

 the female, with the exception that they bear male gonophores instead of female in their 

 smaller ampullae. 



The male gonophores (PL VIII. fig. 3) are sacs containing a number of small ovoid 

 bodies which contain spermatozoa or sperm-cells in various stages of development. The 

 exact structure of these smaller bodies, and their relations to the endoderm, were not 

 determined. 



Errina, Gray. 



The genus Errina was formed by Gray to contain the Millepora aspera of Linnaeus 

 and Esper. Gray gave a short diagnosis of the genus in the Proc. Zool. Soc, 1835, p. 85, 

 from specimens in the British Museum ; and this was supplemented by Saville Kent, 

 in a paper published in the same journal for 1871 (p. 282) by further reference to the 

 same specimens. A specimen dredged by H.M.S. Challenger off the mouth of the Rio 

 de la Plata, in 600 fathoms, is clearly referable to this genus, but represents a new species 

 for which the name Errina labiata is adopted. 



Ccenosteum of Errina labiata (PL I. fig. 7). 



The ccenosteum occurs in the form of arbuscular multi-ramified masses, which have an 

 extreme height, in the specimens obtained, of about 5 inches. The mass of branches 

 and branchlets has a tendency to form an irregular flabellate expansion, which in the 

 largest specimen obtained has a breadth of about 4 inches. The main stems, which 

 are irregularly oval in section, being flattened in the plane of the flabellate expansion, 

 have a longer diameter of about two-thirds of an inch. They, as well as the remainder 

 of the ccenosteuro, are composed of a compact, hard, glistening, white, calcareous tissue. 

 At their bases, this tissue spreads over and encrusts objects to which the coral mass is 

 adherent. In one specimen obtained, the support thus fastened on is a large dead mass 

 of Sporadopora ditfwtoma. The main stems have a surface which appears smooth and 

 even to the naked eye, but when magnified is seen to be scored in all directions 

 by small more or less tortuous canals, which in the recent state contain the superficial 

 ramifications of the coenosarcal meshwork. In specimens in which certain regions of the 

 main stems are dead and somewhat corroded, these scorings of the surface are much 

 more conspicuous than on the recently living regions, and give the surface a roughly 

 engraved appearance. The finer branches have a tendency to develop mostly on one 

 face only of the flabellate expansion, one face of the main stem being frequently devoid of 



