186 BULLETIN OF THE 
two palpi and two pairs of tentacular cirri have also formed, The anal cirri 
have greatly increased in length, and now resemble simple filaments. 
When such a larva is seen from the dorsal side (Fig. 4), four large circular 
elytra can be observed above the parapodia. The sete of the lateral ap- 
pendages of the body terminate in a short joint, as in the youngest larva, 
which has already been described. Rudiments of a fifth pair of elytra, the next 
to appear, can be seen just behind the most posterior of those already formed, 
or between it and the posterior body segment. 
The body of the larva is only partially transparent, although an intestinal 
tract is visible from the dorsal side through the elytra and dorsal body walls. 
The parapodia are well developed, and eight in number on each side of the 
body. Each parapodium is single, undivided, and bears a cluster of long bris- 
tles and a long dorsal cirrus. Each seta has a terminal joint and a basal ar- 
ticulation, which carries a small tooth, as in the younger larvee which have been 
mentioned above. The elytra are still of diminutive size, although they cover 
the bases of the parapodia. The point of separation between the stomach and 
the cesophagus lies just behind and beneath the first pair of elytra. The stom- 
ach sends off lateral extensions in pairs corresponding to the second, third, and 
fourth parapodia.* 
Larva of Nereis sp. (?). _* 
Plate VI. 
The young of a doubtful species of Nereis bears upon the head two lateral 
tentacles, and two short palpi, each with a basal and terminal joint, the latter 
of which is richly ciliated. There are also upon the head three well-developed 
tentacular cirri. The dorsal surface of the head has six eye-spots, two of which 
are placed near the anterior dorsal rim, and four near the posterior. All are 
widely separated from a median line. 
The body is composed of ten segments, nine of which bear pairs of sete. 
The parapodia are very prominent. Each parapodium has a dorsal and ven- 
* The young of an unknown Annelid (PI. IV. Figs. 18, 15°) is easily mistaken for 
the youngest Lepidonotus mentioned above. Although monotrochal it wants the par-. 
alleled rows of black pigment spots situated above (anteriorly to) and below (poste- 
riorly to) the mesial row of cilia. This embryo is exceptional among monotrochal 
larvae, in possessing a single caudal appendage, which is well developed before 
lateral caudal cirri appear. The unpaired median appendage is not unlike that 
found in the mesotrochal larve of Chetopterus, Telepsavus, and Phyllochcetopterus. 
Does this larva belong to the genus Harmothoé, or is it the young of some Bryozoan ? 
+ Compare this larva, as well as the young Nephthys (Pl. 1V. Fig. 12), in this 
particular, with the strange genus Tetraglene Verr. In respect to its color, size, 
cephalic appendages, and other particulars, the two are very different. Many 
specimens of Jetraglene have been taken in our work at Newport. (See Verrill, 
Trans. Conn. Acad, Vol. 1V., Pl. XXV. Fig. 10.) 
An unknown pelagic worm (PI. VI. Fig. 5) was found on several excursions, 
