248 MR. L. N. G. RAMSAY ON 
laterally on each side two pairs of large tentacular civ. 
Fourthly, the eversible proboscis is provided with a pair of curved 
toothed jaws. 
Micronereis as a Primitive Nereid.—The primitive, undiffer- 
entiated condition of the genus is indicated by the following 
points: in the parapodia, the two rami consist of a simple 
setigerous lobe and cirrus alone, without the development of 
“lips” and ligules of the more advanced nereids. The occur- 
rence in one of the Puget Sound specimens of simple setz in 
addition to the compound spinigers may also be a primitive 
feature, as may the absence of falcigers. The prostomium 
and peristomium are fused*, or to put it in another way, 20 
distinct prostomial lobe has been differentiated from the buccal 
“ segment,” and, further, palps and tentacles have not begun to 
be acquired. Thirdly (and this I mention with some doubt, 
having had no opportunity of examining the everted proboscis), 
the proboscis is unprovided with papille, whether soft or hard. 
Advances made by other Nereide.—The main ways in which 
other Nereidz have progressed are in the differentiation of the 
parapodia, the arming of the proboscis with papille, usually 
cornified and hard, and the differentiation of a distinct pro- 
stomial or cephalic lobe, and the development of two pairs of 
sensory appendages (palps and tentacles) borne by this lobe. 
Text-figure 6. 
Parapodium from mid-region of Nereis kerguelensis, for comparison. 
X 20. 
As to the parapodia, the more advanced type is easily to be 
derived from that of Micronereis by the gradual development and 
elaboration of subsidiary protuberances on the surface of the 
original simple setigerous ramus. The setigerous lobes of the 
typical parapodium will thus represent the apices of the original 
rami of the ancestral type, while the elongate ligules and the 
smaller “lips” are secondary developments from the sides of 
* As Quatrefages has pointed out (14, p. 578). 
