42 



BIOLOGICAL RESULTS OF LAST CRUISE OF CARNEGIE 



SPIONID LARVA 



It seems probable that larvae A and B are spionids 

 and quite certain that the next one to be described be- 

 longs in that family. The single specimen is 10 mm long 

 and about 0.5 mm wide. The prostomium (pi. Ill, fig. 42) 

 is definitely spionid in form. It is rounded on the ante- 

 rior margin and its greatest diameter is just behind the 

 anterior eyes. From here it narrows rather rapidly and 

 terminates in a tongue-like part which extends backward 

 over the first somite. A second pair of very inconspic- 

 uous eyes lies near the posterior prostomial margin. 

 The author is uncertain as to whether the part immedi- 

 ately behind the prostomium is composed of two somites 

 or is a biannulate somite. The somite following it (sec- 

 ond or third?) has a small dorsal, and slightly larger 

 ventral cirrus in each parapodium, which also carries 

 a tuft of slender setae, longer than the body diameter. 

 The second setigerous somite has larger dorsal and ven- 

 tral cirri than has the first and setae similar to the first 

 but much shorter. In addition, each neuropodium has a 

 single stout spine (pi. Ill, fig. 43). In later somites all 

 the heavy setae are straight, sharp-pointed, and much 

 heavier than anteriorly. The simple setae in these pos- 

 terior somites are few in number and sometimes have a 

 jointed appearance. This probably is owing to acciden- 

 tal breaks and not to true jointing. 



Collected at station 89 in 50 m. See map 4 (p. 59). 



LARVA C 



The body is 3 to 4 mm long and about 3 mm wide. 

 The prostomium (pi. Ill, fig. 44) is rounded anteriorly 

 with a median marginal indentation. The anterior pro- 

 stomial margin is carried ventrally to form a broad up- 

 per lip. On either side is a massive tentacle, and dor- 

 sally a pair of inconspicuous eyes. Just posterior to the 

 eye on either side is a curved (nuchal?) organ. Between 

 the tentacle and the upper lip, on either side, is a bunch 

 of long cilia (not shown in the figure). The first somite 

 has on either side a ventral tuft of short, sharp, curved 

 setae and a dorsal bundle of much longer ones exactly 

 similar to those in later somites. Under low power these 

 appear smooth, but a higher magnification brings out fine 

 spines scattered over the siurface. On the first parapodi- 

 um there is a lobe between the two seta tufts. In anterior 

 somites the setal arrangement is similar to that of the 

 first, except that there are a few short setae similar to 

 the ventral ones of the first parapodium, lying at the bas- 

 es of the long setae. Some long setae appear in the ven- 

 tral tuft more posteriorly. The setae are several times 

 as long as the body diameter and in the preserved mate- 

 rial are very much tangled. There is a decrease in body 

 diameter toward theposterior end, and a complete ring 

 of cilia on thepygidium. The only par apodial cirri the au- 

 thor could find are the ones lying between the setae tufts. 



This is possibly a spionid but the author is very un- 

 certain of even this identification. 



Collected at stations 41 in 50 m, and 114 and 115 in 

 100 m. See map 4 (p. 59). 



LARVA D 



A single small specimen not quite 3 mm long. The 

 prostomium in outline is a very blunt cone (pi. in, fig. 

 45), its lateral margins being much obscured by large 

 bundles of cilia. On each side of the dorsal prostomial 

 surface are six groups of pigment spots, of which the 

 median pair are much more clearly defined than is eith- 

 er lateral group. There is a single pair of large tenta- 

 cles, one of which was broken off in mounting the speci- 

 men. There is a bundle of long, straight, colorless se- 

 tae on either side of the prostomium, each seta having 

 minute spines scattered over its surface. Similar but 

 slightly smaller setae occur on following somites, and 

 toward the pygidium, where the body is narrower, they 

 become very small. On the ventral side of each parapo- 

 dium is a tuft of shorter curved setae, and there is a 

 cirrus between the two seta tufts. On each parapodium, 

 just posterior to the dorsal seta tuft, is a rather prom- 

 inent oval gill. Beginning on somite 9 long, slender, 

 hooded crochets appear and continue in later somites, 

 being especially prominent toward the posterior end of 

 the body. The pygidium is ciliated. 



These possibly are spionids. 



Collected at station 112 in 50 m. See map 4 (p. 59). 

 What is possibly an earlier stage of this species was 

 taken at station 96 in 100 m. 



TEREBELUDS 



Larval terebellids of indeterminable genera and spe- 

 cies were collected at the surface at stations 2, 31, and 

 36; in 50 m at station 118; and in 100 m at stations 2, 66, 

 and HI. 



"CHAETOSPHAERA" 



Larvae corresponding in appearance to what Hacker 

 (1898, pp. 19-20) named Chaetosphaera. The body is 

 very much rolled ventrally so that prostomium and py- 

 gidium are almost touching, and its most evident char- 

 acteristic is the arrangement of the very large setae. 

 These are nearly as long as the transverse diameter of 

 the body, and spread in such a fashion as to completely 

 cover the dorsal surface and extend anteriorly and pos- 

 teriorly as well as laterally to considerable distances 

 from the body margins. Each seta is curved, its apex 

 entire, and has a row of sharp teeth along its convex 

 margin. The setae are rich chestnut in color and, being 

 so numerous, they give this tint to the entire animal. 

 The prostomium (pi. in, fig. 46) is distinctly bilobed, 

 each lobe being rounded on the anterior margin, and 

 there are two prominent eyes. On either side is a heavy 

 tentacle. The specimen was coiled so that only about 

 eight somites were visible from the dorsal view, and de- 

 tails of pygidial structure were difficult to get. So far 

 as could be determined the pygidium is rounded. 



Collected at stations 89 and 90 at the surface, and 

 110 in 50 m. See map 4 (p. 59). 



