CORYMORPHA NUTANS. 389 



Habifai. — On sandy sea bottoms. 



Baflii/melrical distribution. — Coralline zone. 



Localities. — Coast of Norway, Sars ; Orkney Islands, Forbes and Goodsir; Shetland Islands, 

 G. J. A. ; Firth of Forth, Mr. M'Fie and G. J. A. ; Coast of Nortliunibcrland, Mr. Hodge ; 

 Coast of Cornwall, Mr. Alder and Mr. Peach ; Isle of Man, Mr. Alder. 



Corymorpha nutans is one of the most beautiful of the many beautiful acquisitions of the 

 dredge. When the naturalist is fortunate enough to carry his dredge over the sandy ground 

 inhabited by it, he will usually l)ring up numerous specimens, which may be all derived from so 

 limited an area as to force upon him tiie conviction that the species is gregarious in its habit, 

 though the trophosomes are never united so as to form composite colonies. The specimens on 

 being brought to the surface are always found with sand adhering to their proximal end, which 

 is constantly bent on the rest of the stem, and it is almost certain that while in their natural 

 habitat they live with this end plunged into the sandy sea bottom. 



When freed from the sand, thus adhering to the lower end of the stem, and transferred into 

 a jar of sea water, the Curi/niorjjJia soon begins to fix itself to the bottom of the vessel, and at 

 the termination of about twenty-four hours its base is seen to be surrounded by a delicate web, 

 which closely adheres to the glass, and in a few days has spread itself over a surface of a square 

 inch or more in extent. 



Under the microscope this web is found to be composed of a multitude of fine tubular 

 filaments, which are given off from the stem all round close to its lower end, and then by repeat- 

 edly crossing one another form an entangled web-like tissue. It is almost certain that similar 

 filaments existed in the hydroid while yet undisturbed beneath the sea, where they must have 

 served to fix it to its sandy bed, and that in the act of detaching it they had become torn off", to 

 be speedily renewed on the specimen being again allowed to rest in the confinement of our 

 jars. 



There is no true perisarc, but the stem is invested by a delicate pellicle, so delicate, filmv, 

 and colourless indeed, that it may easily be overlooked; and when the animal is removed from 

 the water the stem, destitute of the support which the Hvdroida usually receive from their 

 firm perisarc, appears soft, flaccid, and gelatinous. Towards the proxinui! end of the stem, how- 

 ever, this pellicle becomes separated from the ectoderm by a considerable interval, and here 

 constitutes a loose filmy sac, in which this portion of the stem is enveloped, and which allows 

 the passage across it of the delicate filaments of adhesion already described. 



By the naked eye the stem is seen to be traversed from one end to the other by uari'ow 

 longitudinal bands. Under a low magnifying power these bands are seen to inosculate with one 

 another here and there, while towards the base of the stem they become fewer and broader by 

 coalescence. They indicate the canals which are excavated in the endoderm of the stem, and 

 which thus show themselves through the more superficial tissues. 



The peculiar short conical papillae which are given off from the stem near its proximal end 

 are arranged in regular longitudinal series, which foUow the course of the longitudinal bands, the 

 stem immediately over each band bearing two alternate rows. 



The planoblasts when they become free are about -^i\\ of an inch in diameter. Their 

 solitary tentacle constitutes one of their most striking features, and has acquired a great develop- 

 ment even before the detachment of the medusa. It consists of a very extensile mojnliform 



