124 G Canadian Arctic Expedition, 1913-1918 



the conchula of Btcidium parasiticum exsert to nearly the same extent, and the 

 edges of its siphonoglyph can cohere, making a tubular form. 



Andres makes it identical with Peachia Gosse, 1855, but P. hastata, the 

 typical species of Peachia, has 10 pairs of mesenteries and a more complex con- 

 chula. 



Philomedusa Mtill. (1860, p. 57, PI. 2, fig. 1) is now believed to be the 

 parasitic larval form of a Mediterranean Halcampella, according to Haddon. 

 But if identical with Bicidium, as Andres supposed, the latter name and also 

 Siphonacttnia are both earlier names. 



The larvae of a species of European Halcanipa (H. chrysanthellum) are also 

 parasitic on jelly fishes (t. Haddon). A closely related species (H. farinacea 

 Ver.) is common on our coast and its larval form should be looked for on our 

 hydromedusiP. 



Siphonactinia parasitica (Ag.). New name. 



Bicidium parasiticum L. Agassiz, op. cit., p. 24, 1859. Verrill, op. cit., p. 31, 

 pi. 1, figs. 14, 15, 1864. Hargitt, Anthozoa Woods Hole Region, p. 239, 

 fig. 2, 1914. McMuRRicH, op. cit., p. 967, pi. 98, fig. 8, 1913. 



Peachia parasitica Yerrill, Proc. Boston, Soc. Nat. Hist., Vol. X, p. 338, 1866; 

 Invert, of Vineyard Sound, p. 739, (445), 1873. Haddon, Proc. Royal 

 Dublin Soc, 1887, p. 475. 



Philomedusa parasitica Andres, Le Attinie, p. 112, figs. 9, 9b, after Verrill, 1884. 

 Plate XX; Figures 2, 3. Plate XXV; Figure 3 (section). 



The following description was made from living specimens parasitic on 

 Cyanea arctica in Eastport harbour, Maine, where it was abundant. 



Bod}' variable in form and size. In full extension elongated, up to 80 mm 

 long and 12 to 14 mm. in diameter; the same specimens in contraction usually 

 tapering to the base. In contraction usually elliptical or ovate, often swollen 

 toward the liasal end; sometimes nearly spherical; no basal disk; aboral end 

 often involuted; true pore seldom visible. 



The visible pore may often be due to a temporary deep infolding of the 

 integument at the center, owing to the contractile movements of the mesen- 

 terial muscles and the circular muscles near it, even when the real pore is tightly 

 closed by its sphincter muscle. 



The column-wall is soft, and it has 12 sulcations corresponding to the 

 mesenteries, visible through the wall; intervals between the sulci are convex, 

 crossed by many transverse wrinkles, and toward the base each has a longi- 

 tudinal row of six to eight minute paler or thin spots, simulating pores, but 

 probably serving as suckers, not always visible to the naked eye. 



The tentacles, in expansion, are about 12 mm. long, thick, often swollen 

 at the base; tips have a terminal pore, often rather conspicuous. Perhaps 

 microscopic suckers are present, for the sides of the body are adhesive to the 

 sides of an aquarium, etc. 



The mouth, when contracted, is often nearly regular, with nine equal lobes 

 or folds, and three others, oVjtusely rounded, standing a little farther back at 

 one end of the mouth forming a conchula in connection with the deep siphono- 

 glyph. But the mouth and lips take various forms, according to the state of 

 contraction. The c(.)nchula can be much protruded at times. It adheres to 

 the jelly-fish partly by means of the mouth-lobes. 



The coldr (.)f the body varies from imiform light flesh-coloiu' to light brown, 

 greenish l^rown, or liver-brown. Sometimes the darker brown specimens have 

 pale flesh-coloured tentacles, with brown tips, a narrow light brown band on 



