ARENICOLA CRISTATA. SABELLA MICROPHTHALMA. 93 



1. Study the structure of the tube; observe how the animal 

 protrudes at either end of the tube. 



2. Observe the diameter and length of the worm, the small 

 number of somites, their great length as compared to somites 

 of Nereis, and the reduced parapodia provided with simple setae. 

 Notice the characteristic collar on the fifth somite, and the 

 funnel at the posterior end, with the anus within it. The mouth 

 is more or less ventral and is overhung by a narrow prostomium 

 surrounded by a peristomial rim. 



A drawing is desirable. 



ARENICOLA CRISTATA. 



This remarkable worm, called the "lug- worm" by fisher- 

 men, belongs to the family Arenicolidse. 



1. Notice the color, and the gradual diminution in size pos- 

 teriorly. Also notice the false annulations between the appen- 

 dages, the arborescent gills representing modifications of certain 

 notopodia, the reduced parapodia, and the character of the setae. 



2. If the buccal region is everted, observe the papillae which 

 cover it. The prostomium is an inconspicuous dorsal knob and 

 it is fused with the peristomium. At the sides of the prostomium 

 is the ciliated nuchal groove. 



3. On what somites can you find indications of neuropodia? 

 of gills? of setae? Notice the cirriform papillae of the "tail." 

 Find large nephridiopores on certain somites about an eighth 

 of an inch below each notopodium. What is the distribution of 

 the pores? 



A drawing is desirable. 



SABELLA MICROPHTHALMA. 



This worm belongs to the family Sabellidae. It builds leath- 

 ery, muddy tubes on piles, among tunicates, algae, etc. 



1. In addition to the general size, form, and color of the 

 worm, observe the reduced condition of the parapodia, and the 

 arrangement and general structure of the branchiae or gills. These 

 structures are modifications of the palps and not of the parapo- 

 dia, as in the other species which have been studied. Observe 



