518 PEOF. GILBERT C. BOURNE ON FIVE 



Edwardsia rakaiy^, n. sp. (Plate 51. fig. 4.) 



Scapiis sepia-brown in colour, divided into eight longitudinal areas by as 

 many well-marked grooves, corresponding to the insertions of the eight 

 macromesenteries. The whole scnpns irregularly rugose or papillate, the 

 rugfe and papillae rorming indefinite transverse rows; the papillae smaller in 

 the grooves, larger in the longitudinal areas between, where they have 

 a warty appearance and are minutely studded with greenish-white vesicles. 

 The distal fifth of the scapus introversible. Capitulum very short, colourless in 

 spirit, with twenty faint longitudinal grooves corresponding to the insertions 

 of the macro- and micromesenteries. Physa oviform, colourless, without 

 longitudinal grooves and raised intervening areas, separated by a well- 

 marked constriction from the scapus. Tentacles twenty in number, colourless 

 in !spirit, 6-7 mm. long in contracted condition, tapering, in contracted 

 specimens usually infolded and crowded together in the bottom of the 

 invaginated part of the scapus, but some may be wholly or partially 

 invaginated. The tentacles in two circlets — the inner comprising eight, 

 the outer twelve tentacles. 



The eight macromesenteries extend from the oral disc to the physa; 

 their longitudinal retractor muscles are enormously developed in the region 

 of, and immediately below, the actinopluirynx, where they form eight pro- 

 minent muscular rolls, but tapering rapidly aborally and ending in thin 

 strands in the physa. Micromesenteries minute, confined to the capitulum, 

 incomplete, with parietal but without longitudinal retractor muscle-fibres, 

 twelve in number, two in each sulco-lateral, lateral, or sulculo-lateral inter- 

 mesenterial interspace. The actinopharynx short, without a differentiated 

 sulcus or sulculiis. A distinct band-shaped endodermic s})hincter muscle at 

 the junction of the capitulum and physa. 



Length of contiacted s})ecimen, IG mm. ; length of the physa, 5 mm. ; 

 greatest diameter, 10 mm. 



Hah. Straits of liakaiya. New Britain. 



The three specimens of this species were fairly well preserved, and I was 

 able to study the anatomy in some detail, both by dissection and in sections. 

 But, owing to the contraction of the very powerful retractor muscles, all the 

 specimens were burst and their shape more or less altered and distorted. In all 

 of them a longer or shorter section of the scapus was introverted, in addition 

 to the capitulum, this being a normal occurrence in Edwardsia and described 

 by Gosse for K. heautempsii (caJlinwrpha, 11, p. 257). In the specimen selected 

 for illustration (PI, 51. fig. 4) tlie scapus has fgiven [way a short distance 

 below the point of introversion, and the lower ])ortion has shrunk back, 

 leaving a portion of the inner wall of the introverted portion exposed. In 

 the two other specimens the scapus had given way below the actinopharynx, 

 and the large retractor muscles projected from the gap thus torn in the 

 body-wall. 



