PANTHALIS PANAMENSIS. S7 



level with the narrowest region of the ommatophores where attached to the lobe 

 bearing the sessile eye. The cirri have the same shape as the median tentacle 

 and are of nearly the same length; each has a dark pigmented patch proximally. 

 No setae were detected on the parapodia of the peristomium. 



The elytra have the usual arrangement, occurring on II, IV, V, VII, etc. 

 Anteriorly they meet and overlap along the median line, but elsewhere they 

 leave the middorsum naked between the two rows. The elytra are thin, delicate 

 and transparent. Jn outline they are very broadly elliptic or nearly circular. 

 Each is weakly campanulate, being depressed somewhat in funnel-form at place 

 of attachment and with the border showing a tendency to turn up over all or 

 part of its circumference. The margin is free from cilia and the surface is 

 smooth. (Plate 12, fig. 5, 6). 



The dorsal cirri are stout at base and strongly acuminate distad, subulate. 

 They extend beyond the distal end of the parapodia but are clearly surpassed 

 by the setae. The ventral cirri are small conical processes attached near or 

 somewhat proximad of the middle of the ventral surface of the parapodium. 

 Each is very short and does not reach the end of its parapodium. The para- 

 podia are conspicuously flattened anteroposteriorly; very deep at base, being 

 there about as deep as long, narrowing subconicaUy distad; the rami very short 

 and scarcely separated, blunt, of about equal extent. 



Acicula two in each parapodium. Pale in color, darker distally than proxi- 

 mally. Stout at base, strongly acuminate distad but with tip not finely acute; 

 with numerous longitudinal fibrillae and distally usually showing many cross 

 striae. The middle setae are stout spines somewhat clavately enlarged and 

 flattened. Distally they are a little curved and end in a short, acute point below 

 which on one side is a series of fine teeth and on the opposite side a long, lash- 

 like process which in most cases in the type has been broken off close to its 

 base. Of the teeth there are ten to sixteen in each series. (Plate 12, fig. 3, 4). 

 The setae of the dorsal series vary much in thickness and length, some being 

 exceedingly fine and capillary, others much coarser, though all are much more 

 slender than those of the middle series. The principal ones much exceed in 

 length those of the middle series. Each presents a long, slender shaft which 

 has distally a lance-like or fusiform enlargement prolonged into a long, very slender, 

 acute tip which is more or less curved. This tip is fringed along both sides, 

 the hairs extending proximad farther on the convex side than on the concave, 

 while distally the hairs increase in length and form a brush-like structure (bi- 

 pinnate, penicillate). In some of the finer setae the hair-like processes of the 



