158 THE ANNELIDA POLYCHAETA. 



300 fms. to surface. Surface temp. 75° F. 13 January, 1905. One specimen. 

 This is a conspicuously larger species than P. simplex and, unlike the latter, 

 shows a distinct annulation of the somites from encircling sulci. It is at once 

 to be separated from the other species in having the large, conspicuously branched, 

 branchiform nuchal organs instead of wholly simple ones. 



TOMOPTERIDAE. 



These are highly peculiar, exclusively pelagic annelids of small size, in which 

 the body is colorless and transparent. The number of somites is small, and 

 between them there are no distinct intersegmental furrows or constrictions. 



The prostomium is fused with the first somite to form a single part which 

 bears in front a pair of short tentacles and laterally behind these two pairs of 

 tentacular cirri, or in some the first pair may be lacking. The second pair of 

 cirri is very long, being from two thirds the total length of the body to longer 

 than it, the first pair on the contrary being mostly small and inconspicuous. 

 Each of the second cirri contains a central seta which extends throughout its 

 length, and a similar seta may occur in the anterior ones. Eyes two. Mouth 

 ventral in position. 



The parapodia are conspicuously extended laterad and each is distally 

 bifurcate, each short ramus bearing a characteristic, flattened, thin cirrus which 

 contains mucus glands suggesting those of the Phyllodocidae. Aside from 

 these glands certain peculiar ''rosette formed organs" may occur in the para- 

 podia and sometimes in the bases of the cirri. These are very useful in classi- 

 fication. Neither acicula nor setae are present in any of the parapodia. 



In some species the body is more or less extended caudad into a slender 

 caudal division, or tail, on which the parapodia are rudimentary or obsolete. 



The blood is colorless. The eggs lie free in the body-cavity. 



The alimentary canal is straight; it presents a large principal division, or 

 intestine, and anteriorly a short pharynx with a short proboscis. 



Two genera are known, Tomopteris and the more recently described 

 Enopteris of Rosa (Public, inst. stud, superiore, Firenze, 1908, 1). Priarea 

 Quoy and Gaimard is the same as Tomopteris. 



