98 TTIE VOYAGE OF H.M.S. CHALLENGER. 



have greatly lessened the probability of Hseckel's view being correct, as in the mature 

 animal the number of the septa is always even, but otherwise very variable. In 

 Sicyonis crassa, on the other hand, we have before us an animal in which the number 

 four is as persistent as the number six in the Hexactinia?, and which, moreover, has the 

 same paired arrangement of the septa as we meet with in the existing hexamerous 

 corals. It is therefore quite possible that the Sicyonidse and Tetracorallia may be closely 

 related. 



Sicyonis, n. gen. 



Sicyonicke, with discoid, flattened body, smooth wall, and alternating reproductive 

 septa and muscular septa. 



Sicyonis crassa, n. sp. (PL IV. figs. 1-9). 



Sixty-four wart-like tentacles placed in two alternating rows ; circular muscle weak ; 

 oral disk covered with numerous fine radial furrows. 



Habitat.— Station 147. December 30, 1873. Lat. 46° 16' S., long. 48° 27' E. 

 Depth, 1600 fathoms. One specimen. 



Dimensions. — Height, 2 cm. Diameter of the pedal disk, 7 cm. ; of the oral disk, 

 9 cm. 



The new species, which I have named Sicyonis crassa, is one of the most interesting 

 Actiniae dredged from great depths, both on account of the constitution of the tentacles 

 and of the arrangement of the septa. The body of the single sj^ecimen before me is cake- 

 shaped, as the transverse measurement of the pedal disk amounts to 7 cm., and that of 

 the oral disk to 9 cm., whilst the height only amounts to 2 cm. The height would, 

 however, certainly be greater in a natural state, as the animal had been very much com- 

 pressed in the packing. 



The body is tolerably tough, more, however, from the thickness of its walls than from 

 the firmness of its tissue. The consistency of the latter is between that of cartilage and 

 of gelatinous tissue, and consists in all parts of the body of a homogeneous fundamental 

 substance enclosing numerous extremely small cells. The fundamental substance is also 

 traversed by numerous bundles of fibrilke, which become very distinct in preparations 

 stained with carmine. These bundles have a wavy course, and become connected from 

 time to time so as to form a reticulate framework. It was not possible to recognise the 

 natural colour of the animal. 



The pedal disk (fig. 2) is marked by radial furrows ; a large number, more than 100, 

 begin at the margin, of which some reach the centre, whilst others do not extend so far. 

 Their course is irregularly waved and indented, and they correspond to the insertions of 

 the septa inside the animal. 



