20 



VERRILL ON THE POLYPS OF THE 



very seldom, if ever, found coated by foreign substances. In form it is very mutable, both 

 ends being capable of great distension or contraction either separately or at the same time. 

 It will often assume a variety of the most diversified forms within a very few minutes. 



This species is very near JR. crassicornis of Europe, having been considered the same by 

 some naturalists, and like it has a wide range of variation in color and form, but it seems 

 never to have the surface, even in littoral specimens, strongly and persistently papillose, 

 like that of the latter. The tentacles, also, appear to be uniformly blunter at the ends 

 than in the corresponding European forms. 



The genera Bobcera and Stomphia of Gosse seem to me to be founded on forms of B. cras- 

 sicornis, and in the present species corresponding forms occur. A large specimen, which I 

 obtained off Grand Menan in 35 fathoms, agrees with the genus Bobcera in all respects, 

 having the same character of surface and furrowed tentacles, which were not withdrawn 

 even after the rough treatment received during its capture ; yet I am unable to separate it 

 from R. Davisii. Another specimen dredged in 12 fathoms, rocky bottom, at Eastport, Me., 

 had the characters of Stomphia. 



This individual had the tentacles in two marginal rows, a convex disk with a broad, ob- 

 long mouth, having a large fold at each end and fourteen radii on one side and fifteen on 

 the other. The walls were apparently smooth. The color of the column was pale pink 

 mottled with vermillion, with a colorless band just beneath the tentacles ; disk light scarlet 

 with a colorless circle near the mouth, the margin of which was bright red ; tentacles trans- 

 parent, bluish white, with a scarlet band near the middle and another close to the end. 

 This specimen, when expanded, was about an inch and a half in diameter and the same in 

 height ; in contraction, low and nearly flat. 



Sub-family Phyllactin^e Milne-Edwards. 

 The characters of this group have been indicated above, page 15. 



Genus Aulactinia Agassiz, MS. 



In this genus the base is adherent, but capable of distension ; column elongated, moder- 

 ately contractile, and capable of involving the tentacles and disk with its summit, but not of 

 contracting into a low cone ; upper part covered with prominent, adherent verrucse or 

 suckers arranged in vertical rows, the uppermost one in each row situated just below the 

 tentacles, larger than the others, trilobed, the lobes again subdivided on their lower sides ; 

 wall near the margin thickened into a fold. Tentacles numerous, subequal, well developed. 

 Mouth (actinostome) with a fold at each angle, one of which is considerably the largest. 

 Internal lamellae well developed, much narrowed near the base, thickened above with 

 strong longitudinal muscles, which serve to contract the disk and tentacles. The walls are 

 thin, leathery, or parchment-like, and but slightly muscular ; digestive sac short and thick ; 

 ovaries attached to the upper part of the lamellae. 



Aulactinia capitata Agassiz, MS. 



Column very long, cylindrical, or more commonly clavate, diminishing from the enlarged 

 summit to a constriction near the base, below which it suddenly expands to the edge of the 

 basal disk, which is narrower than the upper part of the column ; the base is thin and often 



