24S im. BAIRD ON TWO NONDESCETPT I.AUTAL AKXtTLOSA. 



racic segments (?) A row of short spines disposed in a stellate- 

 formed group along each side of the dorsal surface at a distance 

 from the tubercles or feet. Dorsal surface rough externally. 



In the Collection of the British Museum there are two distinct 

 species, both of which I have figured, and of which I beg to ap- 

 pend a description. The names, of course, are only provisional. 



Sp. 1. TnETisELLA FLAVA. (Plate V. figs. 1-11.) 



Body of animal of a yellowish colour, (exclusive of setae) about 

 1 inch in length, about half as broad as long, stout or convex on 

 the dorsal surface. It is composed of 12 segments, which are 

 very distinctly seen on the dorsal (fig. 1), but very indistinctly 

 marked on the ventral surface. Mouth placed on the ventral 

 surface, but there are no traces of eyes or antennae. The dorsal 

 surface is rough and covered with very fine granular-looking 

 bodies, interspersed among which are numerous small calcareous 

 spicula (figs. 9 & 11). The ventral surface (fig. 2) is quite 

 smooth, armed near the anterior extremity with hvo pairs (a 

 pair on each side) of curved hook-like bodies, pointing out- 

 wardly^, like the feet of larvae (fig. 7), and having along the 

 centre a series (about 6 or 7) of rather large circles surrounded 

 on the outer edge by a raised rim. Apparently there is no depres- 

 sion in the centre of the ring, and no appearance of hooks or 

 setae. The feet (?) are disposed only in one row. A bundle of setae 

 or bristles are implanted on the tubercles, which project straight 

 and are rather short and stout ; they are rather numerous, 

 stout, flagelliform, rather long, cylindrical for about one half 

 their length, then suddenly and abruptly terminating in a long, 

 slightly curved, capillary, sharp point (fig. 6). Interspersed 

 amongst these there are several flagelliform setae in each tuft, 

 shorter than the others, with a swollen portion in the mid- 

 dle of the lower and stouter portion (fig. S). The organs 

 Avhich, at first view, I considered metamorphosed branchiae con- 

 sist of a tuft of short spines placed on the dorsal surface of 

 each segment, on each side, about half way betwixt the centre 

 of the back and the feet, and are disposed in a stellate form. 

 Each tuft consists of about from 5 to 7 flattish setae terminated 

 by a short curved spine (figs. 4, 5). 



Length about 14 lines, including the setae on the feet ; breadth 

 about 7 or 8 lines. 



ffab. UnkuoAvn (Old Collection, 3Iiis. Brit.). 



