PISTA. 157 



The rows of hooks commence with the bristles, and in a single series. Each hook 

 (Plate CXXV, fig. 4 a) generally agrees with the type of Nicolea, having two distinct 

 teeth above the great fang, a somewhat narrow space inferiorly, as the process on the 

 anterior outline is high and an excavation exists below it. The posterior outline has a deep 

 dimple, the inferior margin of the base is convex and the prow rounded. The posterior 

 hooks have the same structure but are smaller, and the hispid crowns are proportionally 

 large. After the cessation of the bristles the uncinigerous processes become more distinct, 

 and posteriorly they form in front of the tail a conspicuous series of serrations. 



The tube is of moderate length and composed of secretion strengthened by glittering 

 sponge-spicules and minute Foraminifera, so that it forms a somewhat thick or rough, 

 hirsute tunnel. They seemed to have formed groups. These sponge-spicules constitute 

 a large part of the wall of the tube and form a very efficient protection. The inner 

 secretion is somewhat tough. 



It is probable that such a form as the foregoing would stand for Malmgren's 

 8 done lobata. 



Genus CXLIX. — Pista, Mahngren, 1865. 



Terebella, Linnaeus, Cuvier, etc. ; Terebella? Idalise, Savigny, De Blainville, Grube. 



Cephalic plate with a thick dorsal collar, the margin externally and ventrally joining, 

 after a notch, the anterior fold. Supra-oral fold short. Slender, grooved tentacles. 

 Behind the mouth is a tongue-shaped process. Body rather short, tapered posteriorly 

 to a slender tail with four large anal papillae. Ventral scutes seventeen, besides four 

 or five small terminal scutes. Anteriorly behind the dorsal collar the setigerous processes 

 approach the median line. Behind and above the third and fourth bristle-tufts is a 

 long papilla, and occasionally two are found behind the fourth. Branchia arises on 

 the dorsum of the third segment on each side by a long stem (sometimes two are 

 present), and the distal region is finely branched, the whole forming an arbuscle. 

 Setigerous processes commence on the fourth segment and are seventeen in number; 

 bristles curved, tapered and distinctly winged. The avicular hooks commence on the 

 fifth segment, are in a single row anteriorly, double from the seventh to the sixteenth. 

 Each has a deep basal region, a short, stout main fang with three or four teeth (in 

 lateral view) above it, and a nearly straight posterior outline till it reaches the point of 

 attachment of the powerful shaft. The first six tori have hooks with a long posterior 

 process. The anterior nephridia are small or absent, the posterior with long ducts. 



Marenzeller (1884) reviewed the history of the genus and rectified the synonymy. 



In a careful note on the genus Pista, illustrated by excellent text-figures, Caullery 1 

 (1915) rightly uses both the anterior and the posterior hooks in diagnosis, and shows 

 that the great size of the posterior inferior process really corresponds to the shaft of an 

 ordinary bristle, as had been pointed out in such Sabellids as the Jasmineira-group, 

 thus homologising the parts in both bristle and hook. He places the known forms under 

 two genera,, viz., Pista, Malmgren, and Eupista, Mcintosh, the type of the former being 



1 ' Bull. Soc. Zool. France/ t, ad, p. 68. 



