1910.] NATURAL SCIENCES OF PHILADELPHIA. 385 



lateral fringes only tufts of short brownish hair. A. negligens 5 is 

 undoubtedly its nearest all}' in the Pacific and the resemblance is 

 especially pronounced in young specimens of A. castanea in which the 

 lateral fascicles of notopodial setae tend to be erected, producing the 

 disordered effect that is so characteristic of the known examples of 

 A. negligens, but even specimens 19 mm. long have a greater number 

 of setae than full-grown ones (40-60 mm. long) of A. negligens. 



The examples in this collection vary from 16-74 mm. long and all 

 exhibit the characteristic flatness of the body, the color and prominence 

 of the notopodial setae. Both neuropodial and notopodial setae 

 increase in number with size of the animal. Specimens 16 mm. long 

 have six or seven ventral neuropodials, five to seven visible above the 

 felt besides smaller ones in ventral notopodial fascicles, and nine to 

 eleven in dorsal fascicles. In the ventral notopodial fascicles, in which 

 the increase is most noteworthy, specimens 19 mm. long have nine to ten 

 visible, 24 mm. long about eleven, 30 mm. long twelve or thirteen, 

 37 mm. long thirteen or fourteen, 47-50 mm. long fifteen to eighteen 

 • and 74 mm. long twenty on middle somites; the largest specimen has 

 nine or ten ventral neuropodials. There is also a marked change in 

 the character of the neuropodial setae, those of the youngest and small- 

 est specimens being always much more densely hairy as well as smaller. 

 The dorsal neuropodial setae of specimens 16-19 mm. long resemble 

 those of the ventral series of medium-sized specimens while the largest 

 example not only has the setae of the dorsal series exceedingly stout 

 and blunt, but those of the ventral series of middle segments have 

 through wear lost the apical brush of hairs and the slight terminal 

 curvature and consequently resemble the dorsal setae of medium-sized 

 specimens. There is no doubt that these changes progress with advanc- 

 ing age. 



As is usually true of Aphroditce numerous parasites are adherent 

 to the cuticle, especially of the larger specimens. 



Aphrodita parva Moore. 



Aphrodita parva Moore, Proc. Acad. Nat. Sci. Phila., 1905, pp. 529-532, 

 PI. XXXIV, figs. 3-7. 



In the original account of this species, in comparing it with the 

 closely related A. intermedia Mcintosh it is stated that the latter is 

 15 mm. long. This should have been 5 mm., making the type of that 

 species smaller than the known specimens of A. parva. Until now the 

 latter is known only from the two types taken in the Gulf of Georgia. 



5 Re-examination of the notopodial setse of A . negligens shows that they are 

 often roughened precisely as are those of A. castanea. 



