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



developed, in Cereus sj^inosus, but is not so sharply confined to definite parts as in 

 PhelUa. 



After what has been said in the preface, no further explanation is required as to my 

 reasons for omitting the cinclides in the general character of the family. I shall hence- 

 forward mention the cinclides only in cases where they can be observed anatomically 

 hy transverse and horizontal sections, or by observation with the naked eye. This is 

 possible in a number of species belonging to the genus Calliactis. In Calliactis 

 parasitica there are openings at certain points, having swollen margins, which project 

 somewhat above the surface of the wall ; they can be easily observed even in the dead 

 animal, but they are so distinct in the living Calliactis that they have been already 

 described and figured by earlier naturalists, such as Forskdl (Descriptiones animalium, 

 &c., 1775), Ehrenberg, and Dana. This is not the case in the majority of the Sagartidse. 



Sagartia, Gosse, pro parte. 



Sagartia, Verrill. 



SagartidjB with smooth wall and numerous powerful tentacles arranged in several 

 rows ; with circular oral disk ; without anatomically perceptible cinclides. 



Though I agree as far as possible with Verrill in the limitation of the genera, I restrict 

 the genus Sagartia to forms in which it can be shown at most that the acontia pass out 

 through the wall, but in which, however, no openings can be pointed out, either because 

 they are not preformed or because they are so small and indistinct as to be easily over- 

 looked even with most careful observation. The genus Sagartia is distinguished in this 

 point from Calliactis ; it is, moreover, distinguished from Cereus, Bunodes, and Phellia by 

 the smooth nature of the wall, arising from the absence of papillae and cuticular excretions, 

 and finally from Metndium by the circular shape of the oral disk, and by the powerful 

 development of the tentacles. 



Sagartia, sp. ? 



Body flattened like a cake in the contracted condition ; tentacles nearly two hundred 

 in number, placed in five rows, and decreasing in size from within outwards ; muscles 

 of the tentacles and of the oral disk ectodermal, hardly at all pleated. 



Hahitat.—^tsA:\on 194. September 29, 1874. Lat. 4° 33' S., long. 129° 58' E. 

 Depth, 360 fathoms. One specimen. 



Dimensions. — Diameter of the pedal disk, 4 cm. 



Colour. — (Determined from the spirit specimen) whitish on the whole, the middle 

 third of the wall yellowish-red. 



There was only a single specimen of a true Sagartia in the Challenger material. It 

 was attached to a very porous stone of volcanic origin, but it was so strongly contracted. 



