Actinaria G 125 



the distal third, and a diffuse spot of the same colour at each side of the base. 

 insicle of hps whitish; Ups fi.sh-colour; disk paler with white radial lines 

 running out between the tcxuacles, due to insertions of the mesenteries. 



When well expanded m life, the conchula is often much exserted, sometimes 

 nearly as long as the tentacles. It has three nearly equal, rounded, thick lobes, 

 a simple median and a similar but shorter lateral one on each side, with a deep 

 groove between them (PI. XX, fig. 3). Sometimes the two adjacent hp- 

 lobes, which are less prominent, seem to reinforce the conchula and are then 

 larger than the other lip-lobes, but similar in form. Mouth and lips very 

 changeable. 



This species is not uncommon on Cyanea arctica, from Cape Cod to Nova 

 Scotia, m summer. It is uncertain whether its adult form is yet known. 



The following generic description applies to the specimens that I formerly 

 considered the adult state, but the conchula is so different that it may well 

 be entirely distinct. Moreover, it has 10 pairs of mesenteries. At any rate 

 no intermediate stages have been found during the past 47 years, so far as I 

 know. 



Prof. McMurrich has described a closely aliied species from Puget sound, 

 near Vancouver island, under the name Bicidium cequorece, parasitic oh a species 

 of ^quorea. He found no aboral pore in the contracted specimen, and no 

 conchula, but his figure of the labial lobes is much like those of the same parts 

 in some alcohoUc specimens of our species. No doubt it belongs to the same 

 genus. It had twelve perfect mesenteries. I believe it should be called Siphon- 

 actinia aquorece, in spite of the reduced conchula. 



Bicidiopsis. New genus. 



Form and general appearance much as in Sij^honactinia and Peachia. 

 In life very changeable in form, contracting and expanding its body actively, 

 especially when burrowing. 



The column-wall is soft and naked, but provided with circular muscles, 

 more aboundant towards the ends, both of which are capable of involution. 

 The column -wall usually shows 10 or 20 sulcations due to the insertion of the mesen- 

 teries; in contraction it is much wrinkled. Tentacles usually 12, sometimes 

 8 or 18, of moderate length, rather stout, about equal, nearly in one circle. 

 Mouth large, with large labial lobes. One deep and often tubular siphonoglyph, 

 capable of extension and bearing the conchula. The conchula consists of three 

 thick basal lobes, each surmounted by one or two small papilliform or nipple- 

 shaped processes; often there are five of these, one median and two pairs lateral; 

 but there may be only one lateral pair. 



The sphincter muscle is mesoglceal and but little dilated, even in much 

 contracted specimens. 



The mesenteries are 20, in 10 pairs; 6 pairs are perfect, with thick longi- 

 tudinal muscles, recurved in the distal part; 4 pairs are small and imperfect, 

 though some may unite with the stomodaeum near its bottom; some or all may 

 extend to the aboral end; others to about the mid-length of the stomodaeum. 

 The pairs of imperfect muscles are in the sulcar exocoeles and sulco-lateral 

 exocoeles, as in Peachia hastata, as figured by Haddon (op. cit., 1889, p. 338, 

 fig. 1). Viewed from the inside the 12 perfect mesenteries, and sometimes the 

 others, reach nearly to the centre of the base, which is occupied by a small, 

 roundish, central pore, or in contraction by a thick area of muscular tissues 

 closing it. Toward the aboral end of the column there are some very small 

 and nearly transparent spots, as viewed from the inside, which may be small 

 suckers or else minute pores closed by contraction; they are in rows, but not 

 numerous. 



