104 ANTHOZOA HYDROIDA. 



an inch in height, simple or sometimes sparingly branched, regu- 

 larly zig-zag, slender and flexile, of a clear white colour, often tinted 

 more or less with rose-red, and filled with a dusky granular pulp : 

 the stem, at every flexure, is divided by a single joint and incras- 

 sated, a twisted pedicle originating from the incrassated part alter- 

 nately from opposite sides ; the pedicle consists of 4-6 nearly equal 

 rings, is erecto-patent, tapered slightly and terminated with a bell- 

 shaped cell, perfectly transparent and entire. The polypes, accord- 

 ing to Muller, have twenty-four tentacula * Mr. Couch says they 

 vary " from fourteen to twenty-eight ;" and Van Beneden states 

 the number to be only sixteen. The vesicles are to be found 

 throughout the summer : they originate from the incrassation of the 

 joints at the side of the cells, and resemble an elegant Greek vase or 

 urn, being of an elliptical or ovate shape, with a very short tubular 

 opening on the flattened apex. The ova are comparatively large. 



The polypidom is occasionally tinted of a pink or rose-red colour, 

 an accident which is not unfrequent with the Sertularians in 

 general, especially with Sertularia abietina and pumila. On 

 what the colour depends has not been ascertained. Some specimens 

 so tinted retain the colour after being dried, while others lose it. 

 The nature of the habitat has apparently no influence on it, for I 

 have often observed coloured and colourless specimens on the same 

 stone and sea-weed. The specimens are sometimes only partially 

 coloured, red in one portion, and of the ordinary yellowish-brown 

 hue in another : " in such instances as have come under my ob- 

 servation, the red was generally, if not always, the basal portion." 

 W. Thompson. 



3. L. GELATINOSA, stem filiform, elongate, branched, the 

 branches divaricate, scattered, panicled ; cells on rather long 

 pedicles, campanulate, with an even rim. Dillenius. 



PLATE XXV. Fig. 3, 4. 



Var. a. Stem a single tube, subramose. 



Var. &. Stem compound, ramous. Plate XXVII. Fig. 1. 



Corallina confervoides gelatinosa alba, geniculis crassiusculis pellucidis, Rail Syn. 1. 

 34, no. 7- Corallina filiformis ramosa pedunculis calyculorum contortis, Ellis 

 Corall. pi. 38, fig. 3 ; and p. 23, pi. 12, fig. c. C. Sertularia gelatinosa, Pall. 



* " In perfecta animalis extensione duodecim tentacula posteriora reflexa cingunt 

 cellulam, anteriora protensa in formam campanulas radiates cingunt capitulum."- 

 Muller. 



