1905.] NATURAL SCIENCES OF PHILADELPHIA. 295 



From A. aculeata it departs in many and striking characters. Per- 

 haps the most important is the altogether different form of the large 

 notopodial spines. In the former they are acute, rigid needles whose 

 points project stiffly a short distance above the felt, and are capable of 

 inflicting ciiiite painful wounds. In the latter they curve over the back 

 to or beyond the middle line and are soft, flexible but friable, and ter- 

 minate in acute and hooked tips. It is interesting to note that 

 Mcintosh states that .the young of A. aculeata possess setse of this sort, 

 which are later replaced by the acute spines. But A. hastata and sev- 

 eral other species retain the more primitive form throughout life, unless, 

 of course, as frequently happens, they are accidentally injured. In 

 A. aculeata the number of neuropodial setae is constantly greater in 

 the middle and ventral rows and sometimes greater in the dorsal row, 

 and they are stouter, less acute and differ otherwise in form. The 

 lateral fringe of hairs is brilliant green in A. aculeata, pearl color or 

 reddish in A. hastata, and there are other minor differences. A dissec- 

 tion of a single example of A. hastata mdica,tes identity in the internal 

 anatomy of the two species. The complete description follows: 

 Aphrodita hastata sp- nov. 



The size is large, examples of 125 mm. long and 40 mm. in maximum 

 breadth at somite XII, exclusive of the setae, being common, though 

 none equalling the maximum size of A. aculeata has been seen. Exam- 

 ples of 70 to 125 mm. have 40 or 41 somites, the last 15 or so being very 

 small and comprising not more than one-eighth of the total length. 



As in A. aculeata, the form is robust and strongly arched in the ante- 

 rior half, the last fourth becoming slender and tapering rapidly in both 

 planes. The ventral surface is relatively smooth and pale, the brown- 

 ish spherical papillae being few in number but increasing toward the 

 sides and becoming numerous on the dorsal, anterior and posterior 

 surfaces of the parapodia. Hidden, of course, beneath the dorsal felt 

 are 15 pairs of elytra and the dorsal fimbriated organs, both arranged 

 as in ^. aculeata. 



The prostomium is orbicular obovate; the greatest width, which lies 

 near the anterior border, is about equal to the length and the posterior 

 half tapers rapidly to a width of about one-third the maximum. The 

 two minute, closely approximated eyes on each side are placed just 

 anterior to the greatest breadth of the prostomium and separated by a 

 wide median interspace. Although apparently quite variable the facial 

 tubercle is nearly always considerably shorter than the prostomium, 

 strongly compressed below, broad and usually with a median groove 

 above. While the usual spherical papilla? stud its surface it is otherwise 



