1910.] FROM MERGUI ARCHIPELAGO. 811 



Thyrosctphus eegllaris Jiiderholni, 1S96. (Plate LXXVII. 

 fig. 7.) 



{T. ceqiudis Warren, 1908.) 



TROpnosoME. The specimens are somewhat larger than those 

 originally described, sometimes ahnost 20 cm. in length, while the 

 branches maj^ reach a length of 45 mm., in i)lace of tiie maximum 

 of 18 mm. given by Jiiderholni. 



The species is readily distinguisheil from T. viliensis by the 

 presence' of a very distinct operculum, accompanied by deep bays 

 iound the margin; further, the bright rim runs in this case 

 much nearer to the edge, and is not so pronounced, while the faint 

 ringing at the internodes is more marked. The joints, varying 

 in number, which are said to occur on the peduncle, are only 

 occasionally present (though sometimes up to three or four were 

 observed), and even then they are not essential to tlie specific 

 structure, for they are due to the destruction of the hydrotheca, 

 and to the subsequent regeneration of a new hydrotheca from 

 within the remains of the old one, the apparent joints being the 

 reliquias of former calycles. No specific value can attach to 

 these accidental " joints," the like of which I have already 

 observed in Thyroscyphus simplex = tridentatus (1909, p. 75, 

 fig. 1 h) and in Lytoscyphiis marginatus ; but in T. ramosits the 

 semblance of a twist occurs in the peduncle. 



The minute structure of the cfcno.sarc is obscured by the 

 presence of opaque gi-anules which occur in great abundance. In 

 these specimens the hydi-anth is attached, not to a continuous 

 ridge, as in the specimens from Katal, which Warren has de- 

 scribed as T. cequalis (and which I am unable to <listinguish from 

 T. regularis), but to a row of small chitinous prominences which 

 runs round the inside of the hj'drotheca in an exceedingly 

 sinuous curve, having two maxima, one on the adcauline, the 

 other on the abcauline surface, and two lateral minima. 



GoxosoME. Gonangia, which have not previously been described, 

 were found on a single colony from Station 25 (PI. LXXVII. 

 fig. 7). The coenosarc has disiippeared, but the perisarc is in the 

 form of a long cylinder, larger even than that of T. iorresii (see 

 Jiiderholni, 1903, p. 273). Very indefinite and irregular wrinkles 

 appear on the perisarc. The insignificant stalk of the gonangium 

 arises from the projection of the internode upon which a hydro- 

 theca is perched. 

 Dimensions : — 



Branch, diameter O'SG mm. 



Distance between hydrothecjo I'lB to PS mm. 



Hydrotheca, depth 0'9t> mm. 



„ breadth at mouth 0-63 mm. 



Peduncle, diameter 0-20 mm. 



Gonangium, length 3 mm. 



,, breadth 1mm. 



Localities. A larije bunch of colonies from St. 22, Hastings 



[13J 



