256 T. A. STKPIIENSON 



Species : 



H. producta, .Stinip., 1856. p. 110, is the gciiolypu, and {)erhaps, 

 others should also he included. (See Verrill, 1891t.) 



Harenactis, Torrey, 11K)2. 



Ilyanthidae with a physa whiuh eau flatten into a disc and stick to 

 something. The body may attain groat length ; it is smooth, but has 

 a vertical row of cinclidcs in the upper part of it, corresponding to each 

 eiidocoel and exocoel. No conchula. No sphincter. Twenty-four 

 simple tentacles. One siphonoglyphe. Longitudinal musculature of 

 tentacles ectodermal. Mesenteries all inacrocncmes, twelve pairs, only 

 the six primary pairs usually fertile. 



Species : 



H. attenuata, Torrej-, 1902. 



Peachia, Gosse, 1855. 



Siplionactinia , Dan. and Kor., 1856. 



Ilyanthidae with a physa, in which there are typical!}' cinclidcs. 

 Column can be thick, or can become vermiform by attenuation (see 

 Part II, Text-fig. 7, a), without verrucae, A trifid conchula (which may 

 have further subdivisions beyond the three main ones) is usually present 

 in connexion with the opening of the one si])honoglyphe. No sphinctei'. 

 Tentacles simple, eight or twelve. Mesenteries ten pairs (or six pairs in 

 younger specimens) ; usually six pairs perfect, with strong diffuse 

 or circumscribed-diffuse retractors, gonads, and filaments — more rarely 

 only the eight protocnemes are perfect, but the other primary couples 

 have their filaments and retractors. There are four secondary imperfect 

 pairs without gonad and filament, but they have strong retractors and 

 are not microcnemes. 

 Species : 



P. hastata, Gosse, 1855. p. 294. (See also Gosse. 1860, p. 235 ; 

 Faurot, 1895. p. 136; Haddon. 1889. p. 337; Stephenson, 

 1920 a, pp. 446, &c. ; Haddon and Dixon, 1885.) 

 V. uudata, Go.sse, 1858. p. 418; 1860, p. 239. 

 P. triphylla, Gosse, 1860. p. 243. (See Hornell. 1894. p. 78.) 

 P. q u i n q u e e a p i t a t a . McMurrich 1913. 

 P. koreni. McM.. 1893, p. 144. 

 P. hi Hi, Wilsmore, 1911, p. 39. 

 And probably others. 



1 have cast the definition so that it covers the aberrant 

 P. hi Hi as well as the typical forms, but it would not be 

 surprising to find that that species merits separation from the 



