CLASSIFICATION OF ACTINIARIA 255 



IiiYANTHUtf, Forbes, 1840. 



Ilyanthidae with a pliysa. Body-form may be thickisli. witliout 

 suckers, but there may be patches of cuticle. Margin of scapus forms 

 a collar with a narrow capitulum above it. Tentacles simple, in 3 cycles, 

 from about 28 to 36. No conchula. Mesenteries the same in number as the 

 tentacles, all macrocnemes (perfect, with circumscribed retractor, and fila- 

 ment), but not all fertile. Seven tentacles form the priuTary cycle ; these 

 are held permanently over the mouth, and divide up those of the outer 

 cycles into radiating groujjs. The arrangement is exactly bilateral, and 

 not radial; one directive tentacle is a 'primary, the other a secondary. 

 Tentacles of cycle 3 the longest. 

 Species : 



I. mitchelli, Gosse, 1853, p. 128 ; 1860, p. 232. 



? 1. acoticus, Forbes, ' Ann. N. H.', i. v. 183. 



The only species to be certainly referred to this genus is 

 1. mitchelli, which I ha\e been able to stndy alive and 

 anatomically. It is a miique and extraordinary form, and 

 further details about it Avill, I hope, be shortly forthcoming. 

 It is clear that I. part he no pens, Andres, is something 

 quite different from I. mitchelli, and merits at least a 

 distinct genus, and as it seems to me a distinct family ; see 

 Andresiidae for further detail. 



Eloactis, Andres, 1883, p. 464. 



Ilyanthidae with a physa which may adhere slightly. Column without 

 verrucae, its upper margin well marked. Tentacles twenty, capitate, 

 not fully retractile, the outer largest ; tentacular longitudinal muscle 

 ectodermal ; tentacle-heads especially rich in sting-cells. No con- 

 chula. No sphincter. Mesenteries ten pairs, all macrocnemes • (see 

 Part II, Text-fig. 9), probably all fertile. One siphonoglyphe. 

 Species : 

 E. mazeli, Jourd., 1880, p. 41. (See Faurot, 1895, p. 152 ; and 

 Rees, 1913, p. 70.) Perhaps others. 



Haloclava, Verr., 1899, p. 41. 



Ilyanthidae with body which may be long. Base physa-like but 

 capable of adherence to small objects. The body has rows of adhesive 

 suckers above. There is some sort of sphincter. Tentacles twenty, 

 usually clavate. No conchula. Mesenteries ten pairs, all perfect, 

 very muscular, but six pairs are larger and form a primary cycle. 



