438 THE ANNELIDA POLYCHAETA. 



Each is bilimbate, with apical portion smooth and entire. Uncini begin on the 

 fifth somite (third setigerous) and are present on all succeeding ones except 

 a few at the caudal end. Each uncinus has the long, shoe-shaped base char- 

 acteristic of the genus. The small, button-shaped process on the dorsal side at 

 or scarcely removed from the end, with below this on the end a sUght angular 

 prominence. At the apex there are two smaller teeth above the principal one, 

 which is very long. 



Locality. Panama: Perico Island. 12 March, 1891. 



Terebellides M. Sars. 



Beskiv. og lagtt. 1835, p. 48; Malmgren, Ofvers. K. akad. Forh., 1865, p. 396. 



Terebellides eurystethus, sp. nov.' 

 Plate 80, fig. 7-15. 



The color is yellow throughout. 



The thorax is broad anteriorly, the broad region narrowing moderately 

 cephalad and abruptly caudad near the twelfth setigerous somite, the posterior 

 setigerous somites being nearly uniform in diameter with those of the abdomen. 

 The body is dorsally convex and ventrally flattened, as usual. The abdomen 

 is ventrally longitudinally furrowed. The maximum width of the thorax in the 

 type is, exclusive of the parapodia, 6 nun. The width of the last .setigerous 

 somite is 2.5 imn., this being near the width of most of the narrower region of 

 the body. The length of the type to the end of the last setigerous somite is 

 about 30 mm. The total number of somites in the paratype is sixty, or about 

 that number. 



The prostomium is a prominent lobe which widens forward like the end of a 

 trumpet, the anterior end being broad and flat, with the edge wavy or folded. 

 The disc bears numerous tentacles, which are very short, fine, and fiUform 

 throughout their length. 



The prostomium ventrally forms a large and conspicuous lower lip, which is 

 depressed transversely near the middle of its length and is widened distad, its 

 lateral angles projecting laterad over the base as conspicuous, more or less 

 angular, processes. The anterior edge is long and nearly straight. 



The branchia has nearly the general form and proportions as in T. stroemi. 



' (ipv!, broad, and aTrjBos, chest. 



