NATURAL HISTORY OP THE GENUS HERO. 
105 
l3. With secondary branchiae. 
5. Dero limosa, Leidy (15). PI. V. figs. 11-16. 
Dero philippinensis, Semper (26). 
Segments 55-60. Contractile loops 5, the last much the 
smallest. The branchial area with dorsal lip, each angle bearing 
a secondary branchia, short, cylindrical, and containing a loop of 
blood-vessels. Branchial processes as in D. obtusa, but longer 
and narrower. 
The foregoing species appears to me, for reasons already 
stated, to be identical with Prof. Leidy’s ; and there is no 
difference which cannot be explained on the grounds laid down 
(p. 100). Should the species under notice hereafter prove to 
be distinct from Prof. Leidy’s, it will stand as new, unless 
indeed it be the same as Prof. Semper’s JD. philippinensis, as on 
the same considerations seems probable ; though the latter may 
possibly be identical with the species next to be described, a point 
which cannot be settled in the absence of a figure of Prof. Semper’s 
worm. 
6. Dero acuta, Bousjield (5). 
Characters nearly as in D. limosa ; but the branchiae much 
longer, obovate in form, with pointed apices ; length about 4 or 
5 times the greatest breadth. 
Only two examples of this species have come under my notice 
from the localities already mentioned (p. 103). A careful search 
during the present season has been unsuccessful ; so that no 
figure can be given; but there will be no difficulty in recognizing 
the worm from the description above. 
y. With secondary branchiae and palpi. 
7. Dero eurcata, Oken (20). PI. V. figs. 17, 18. 
Das geschmeidige Wasserschlanglein mit zwey Grabelspizen, 
JRdsel (24). — Dero palpigera, Grebincky. — Dero Rodriguezii, 
Semper (26). 
Segments 35. The branchial area more funnel-shaped than in 
the other forms ; the dorsal lip not divided off, but bearing sup- 
plementary branchiae at its junction with the alae. The integu- 
mental layer at the tip of the branchial area prolonged into two 
palpi of varying length, non-ciliated, extra- vascular. Branchiae 
nearly cylindrical ; contractile loops five. The first dorsal bristle- 
bundles in the fifth segment. 
