38 Armelida Ghcetopoda 
finger shaped, extending a little beyond the feet. Ventral 
cirri swollen at base, outer third suddenly attenuated. 
Setae, in two bundles. Upper bundle made up of two or 
three compound setae, appendix short, bidentate (f 76), 
and one simple seta (f. 77), long, acute, with a narrow bor- 
der ; one straight black acicula (f. 79). Lower bundle, 
two or three of the compound bidentate setae ; one com- 
pound seta (f. 78), with a long, narrow, acute appendix; 
one bidentate acicula (f. 80). 
(6.) In the next stage there is a slight depression of the 
anterior margin of the head, one antenna, as in f. 81; the 
bidentate setae have disappeared from two or three of the 
anterior segments, the other forms (figs. 77, 78) are more 
numerous. In other respects same as (a). Length, 2.5-4""". 
(c.) As a next step, the anterior emargination becomes a 
little deeper, and a shallow median depression extending 
back a short distance, above and below (f. 81), indicates 
more clearly than before the future division of the head 
into palpi. Simple finger-shaped branchiae appear on the 
10th setigerous segment. On a specimen with 36 setigerous 
segments there are 13 pairs of branchiae; of these the first 
two, and the last three, are shorter than the others. 
Length, 4"""". 
(c/.) In the next form, there are three antennae. In one 
specimen the lateral antennae are mere buds (f. 82). Eyes 
four to two. The median eye disappears first, next one or 
both of the anterior eye specks, so that on specimens other- 
wise the same there may be two, three, or four eyes. The 
division of the head into palpi becomes better marked. The 
shape of tho feet becomes somewhat changed; the bidentate 
setae gradually disappear from the anterior segments, un- 
til on the largest of the series they are found only on the 
posterior third ; a second straight acicula is added to the 
upper bundle of setae, and a second bidentate acicula to 
