94 ANNELIDA. 



the two irregular rows of small ocelli or eye-spots. Account 

 for the presence of eyes in their position. A pair of short tenta- 

 cles can be seen by spreading the branchiae aside. 



2. Find a collar which is used in smoothing the orifice of the 

 tube. This is a peristomial structure and is so extensively 

 developed in some species as to hide the prostomium entirely. 



3. Identify eight setigerous somites anteriorly, in which 

 the capillary setce are in the notopodium and the uncini are in 

 the neuropodium. With the peristomium they form a " thorax" 

 of nine somites. In the somites which follow, the "abdo- 

 men," observe that the uncini and the capillary setae stand in 

 the reverse order. 



4. Find the ventral shield-glands. A furrow (sulcus or 

 fsecal groove) divides them into pairs toward the posterior end 

 of the worm. 



A drawing is desirable. 



HYDROIDES. 



This is a member of the family Serpulidse. Study living 

 specimens and their heavy calcareous tubes. Notice the banded 

 branchice (modified palps) and the dorsally placed operculum, a 

 modified gill filament. Look for "eyes" on the gill filaments. 



A drawing is desirable. 



Hatschek: Entwicklung der Trochophora von Eupomatus uncinatus, 

 Philippi. (Serpula uncinata.) Arb. Zool. Ins., Wien, 6, 1886. 



SPIRORBIS BOREALIS. 



This animal is also a member of the family Serpulidse. 

 Specimens are very abundant along the shore, attached to Fucus. 



1. Study the tube and notice the way in which it "parallels" 

 the form of a small snail-shell. 



2. Remove a live specimen from the Fucus on which it grows 

 and crack the tube away with a needle. Study the animal in 

 a watch-glass with a low power. Identify the gills, the opercu- 

 lum (which serves as a "brood-pouch"), the setce, and the collar. 

 Are there any "eyes" on the gills? 



