POLYCH^TA. — BENHAM. 189 



Physalidonotus rugosus, sp. nov. 



(Plate xxxviii., figs. 16-22 ; Plate xxxix., figs. 23-25.) 



A stout oval Polynoid, measuring 48 mm. in length by 

 22 mm. across the elytra, and 27 nmi. over the ventral 

 chsetae. The diameter of the body alone measured over the 

 ventral surface is 10 mm. The height at about the middle 

 is 9 mm. 



The 12 pairs of elytra completely cover the back and 

 overlap considerably in the fore and aft direction. They 

 are attached firmly, are of a cartilaginoid consistency, shiny 

 white below. The region of each which is covered by its 

 predecessor is smooth and nearly white ; the rest of the 

 exposed surface is extremely rough, with smaller and larger 

 tubercles and papillae of various shades of brown ; but a 

 small area just in front of the '' areola" is rather conspicuous, 

 owing to the pale ground colour, with small, pale tubercles. 

 The external or lateral region is thinner than the rest, and 

 where it covers the parapodium may be folded upwards 

 owing apparentl}' to the contraction of the body wall and 

 elytrophore. 



The " areola," or scar as it is sometimes called — that is, the 

 area by which it is attached to the elytrophore, is an elon- 

 gated oval, transverse to the long axis of the body. At the 

 mesial or upper end of this areola is a small group of 4-6 

 long sub-cylindrical spinose papillae, terminating in an 

 enlargement covered with conical spines (PI. xxxviii., fig. 19). 

 These "areolar papillae" measure from l.O to 1.5mm. m 

 length. 



In addition, there may be one or two isolated similar 

 papillae near the external end of the areola. 



The entire free edge, i.e., the lateral and posterior margins, 

 is fringed with similar papillae, shorter on the posterior but 

 longer on the lateral edge, where they measure from 1 .5 to 

 ] .75 mm. Moreover, they are not confined to the latter 

 edge, but some 2-3 rows of rather smaller papillae occur on 

 the surface of this region close to the edee (PI. xxxviii., fig. 

 18). 



These long laterally placed papillae form a very conspicuous 

 fringe overlying the notopodial chaetae. They are pale, 

 transparent, and probably colourless in life. 



The shape of the elytron in the mid-body is roughly a 

 rectangle with rounded corners, and with a sfight excavation 

 on the anterior margin ; its long axis is transverse to that of 

 the body. 



