126 G Canadian Arctic Exjiedition, 1913-1918 



This genus seems closely related to Peachia Gosse, especially to P. Iriphylla, 

 wliich has a three-lobed conchula. But that was not the typical species. The 

 earlier described species, L. hastata, must be taken as the type of Peachia. 

 That species has a far more complicated conchula, but its mesenteries are arranged 

 in essentially the same way, though the longitudinal mesenterial muscles are 

 very different in form, being recurved, much wider and not so thick, and 

 pinnate instead of reniform or crescent shaped as in our species. 



Both have two cycles of mesenteries, those of the second cycle being un- 

 developed in the sulcular lateral exocceles, so that there are but 10 pairs of mesen- 

 teries in each genus. But the arrangement is strictly hexamerous. The failure 

 to develop two pairs of mesenteries of the second cycle does not change the 

 regular hexamerous condition of the six primary perfect pairs. 



The only external character for the" separatiori of Bicidiopsis from Peachia 

 that can now be relied upon is the great difference in the conchula. 



In P. hastata the conchula is described and figured by Gosse (Actin. Brit- 

 anica) as very large, consisting of two large rounded lobes, bearing 12 to 20 

 processes, more or less divided, and therefore very different from that of our 

 species. He states positively that it has a basal pore, as in our species. 



iNlcMurricli failed to find a terminal ])ore in preserved specimens that he 

 described under the name Peachia quiiiquecapitata, from Nanoose bay, Van- 

 couver Island, in 15 to 2!i fathoms (op. cit., 1913). Probably the pore was 

 tightly closed in his specimens. His species belongs to Bicidiopsis, as here 

 defined. 



Andres described a species, evidently of this genus, under the name Siphon- 

 acttnui tricapitata, but having only three papilliform processes on the conchula. 

 One of his specimens had 18 tentacU's; the other two had 12 tentacles each. 

 He did not descrilie its internal structure but gave a good coloured figure. 

 It closely resembles B. tuhicala in foi'm and colour. It should be called Bici- 

 diopsis tncapitala. 



I have separated this genus from Siphoiiactinia on account of the presence 

 of 20 nn'senteries, insteail of 12; and because of the more elaborate conchula, 

 which carries a group of papilliform lobules, not fo\uid in that genus. 



Bicidiopsis tubicola. New species. 

 Plate XX; Figure 1. 



The following description was made from two living specimens taken by me 

 in the harljour of Eastport, Maine, at low water mark of a verv low "tide, 

 burrowing in sand and gravel, up to the tentacles. 



The liody of the larger specimen in partial exi)ansion was nearly cylindrical, 

 about three times longer than broad, obtusely jounded and perforated at the 

 l)ase, without a basal disk. The l)ody-walls are salmon-colour and somewhat 

 translucent, allowing the mesenteries to show through as whitish hnes. The 

 intervals between these lines are swollen and transversely corrugated by wrinkles; 

 posteriorly the surface appears somewhat reticulated bv wrinkles," enclosing 

 polygonal areas. No suckers are ordinarily visible, but the creature can adhere 

 to the side of a glass dish by the surface of the body, indicating the presence of 

 minute or retractile suckers; minute round pits," which may be contracted 

 suckers, are often visible with a lens on the preserved specimens. 



Tentacles twelve, large, stout, tapei-ing, but usually obtusely pointed. 

 Then- colour is pale salmon, brown at the inner base, and crossed by "four bands 

 of light brown. The disk is small, brownish around the mouth, outside of this 

 it has a circle of pale salmon, and is then brownish at the bases of the tentacles. 

 The mouth is salmon-colour insid(\ It is furnished with a large, prominent, 



