386 Transactions. 



visible cinclides except when the acontia are ejected. The colour is 

 white. 



Sphincter Muscle. — There is a spindle-shaped thickening of the meso- 

 gloea in the upper part of the column, causing a slight bulging of the wall. 

 In the sphincter the muscle spaces are very close together, but otherwise 

 this muscle is of the usual sagartian type. 



Tentacles.— There are 96, in four cycles, 12 + 12 + 24 + 48 = 96. 

 In colour they are opaque-white, like the column ; in shape, conical and 

 tapering. The length is rather more than half the diameter of the disc. 

 At the base of each tentacle is an incomplete ring of yellow pigment, the 

 open part directed inwards and the outer circumferences of 

 / \ the rings close together, so as to make an almost continuous 



^ (§)(§) I'i^g ^^ yellow round the top of the column under the ten- 

 tacles (fig. 7). Nematocysts are numerous in the tentacles. 

 Fig. 7. 'pj^g ectoderm and endoderm are relatively thick, the me- 



sogloea being reduced to a mere streak. The muscle-bearing 

 processes on both sides are few in number. The nerve-layer is compact, and 

 appears almost as a line in cross-sections. There are numerous large 

 irregular spaces in the ectoderm. 



Oral Disc. — Colour white, as in the tentacles and column. Mout'j is 

 set on a peristome. The stomodseum is white, and there are 2 siphono- 



Mesenteries. — Owing to the difficulty of killing and fixing this species 

 I was unable to determine accurately the number and arrangement of the 

 mesenteries. 



Acontia. — These are emitted reluctantly, some 

 through the mouth, others from cinclides which are 

 placed on the column just under the yellow line at the 

 bases of the tentacles. The acontia are long, and con- 

 tain very large numbers of nematocysts, together with 

 many nerve-cells. The processes of the nerve-cells run 

 between the closely packed nematocysts (fig. 8). 



Habits. — This species lives in the chinks among the -piG. 8. 



" roots " of Lessonia. It is impatient of light. 



Dimensions. — In full expansion it is 12 mm. high and 10 mm. in dia- 

 meter. The pedal-disc is rather wider than the column. 



Distribution. — Of the genus — British Isles, New Zealand. Of the species 

 — Island Bay. 



Genus Halcampactis (Farquhar). 



This genus, which I consider to be closely allied to Ch and r actinia or to 

 Paraphellia, will probably become the type for a new subfamily of sagartiads. 

 By its author it is ascribed to the family Halcam/pidw. At the same time 

 he considers it as constituting a link between that family and the Sagartidce. 

 I have not been able to find Farquhar's Halcampactis mirahilis, though I 

 made one search in company with Mr. Farquhar, and have been out several 

 times myself and with Professor Kirk, the original discoverer of the animal. 

 I have, however, seen the original sections of H. ■mirabilis, but until I have 

 been able to rediscover the species described by Farquhar I prefer to simply 

 place the genus provisionally in the Sagartidce. While searching for Hal- 

 campactis mirabilis I found three specimens of the species to be now described, 

 a species which probably belongs to the same genus. 



