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



besides which there are twelve pairs of imperfect septa of the third order. Septal stoniata 

 are wanting throughout. The parietobasilar muscle reaches to about one-fourth of the 

 height of the wall, where it gives rise to a circular constriction. 



All the septa bore reproductive organs. As the animal examined was a female, I 

 was able to prove the existence of the filamental apparatus, which most resembles that 

 of Calliactis pa7xtsitica. A conical process rises on the surface of the ovum, the point 

 of which pierces the supporting lamella, and reaches to the free surface of the epithelium. 

 The specimen was, unfortunately, not sufficiently well preserved to determine whether 

 the process is formed of special cells, or is part of the ovicell itself. 



Paractis excavata is perhaps allied to the Actinia peruviana of Lesson (Voyage de 

 la Coquille, Zoologie, torn. ii. part ii., 2, p. 75 ; Zoophytes, pi. ii. fig. 3) ; the number, form, 

 and arrangement of the tentacles, and the expansion of the body at the upper end is 

 common to both. The longitudinal furrows on the outside of the wall, which are so 

 distinct in Paractis excavata, are however wanting in the Actinia (Paractis) peruviana; 

 there are said to be merely " quelques plissures brunatres " present on the lowest section 

 of the wall. 



Dysactis, Mdne-Edwards. 



Paractidaa with smooth body surface, without papilla?, and without marginal spherules ; 

 tentacles very unequal in size, the inner essentially larger than the outer, completely 

 retractile. 



I have kept essentially to the definition of the genus Dysactis, as given by Milne- 

 Edwards ; differing from him only in one subordinate point, for while he limits the 

 number of the rows of tentacles unnecessarily to two, I make no definite assertion on this 

 point. I differ more decidedly from Verrill (Mem. Boston Soc, vol. i. p. 26. 1866-69), 

 who has placed the genus Dysactis among the Antheadae, and consequently makes it the 

 most important character of the genus, that the wall cannot be drawn over the oral disk 

 and tentacles. I do not understand why VerrUl should differ in opinion from Milne- 

 Edwards, who has placed the genus Dysactis among the forms with retractile tentacles. 



Dysactis crassicornis, n. sp. (PI. VII. figs. 6-12). 



Height of the body rather greater than the breadth ; tentacles short, thick-walled 

 and conical, arranged in four to five rows, and decreasing in size from within outwards, 

 24 tentacles in the first row, 24 in the second, 48 in the third, &c. 



Habitat— (a) Station 312. January 13, 1876. Lat. 53° 38' S., long. 70° 56' W. 

 Depth, 10 to 15 fathoms. One specimen, (b) Station 313. January 20, 1876. Lat. 52° 

 20' S. long., 68° 0' W. Depth, 55 fathoms. Four specimens. 



Dimensions. — Height, 4-7 cm. ; diameter of the pedal disk, 3-7 cm. 



I made Dysactis crassicornis the subject of detailed examination, as there were 



