ARENICOLA CRISTATA. SABELLA MICROPHTHALMA. 95 



ARENICOLA CRISTATA. 



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

 men, belongs to the family Arenicolidae. 



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 papilla? 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 seta?? Notice the cirriform papilla? 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. 



Gamble and Ashworth: The Anatomy and Classification of the Areni- 

 colidse with Some Observations on their Post-larval Stages. Quart. 

 Jour. Mic. Sci., 43, 1900. 



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 brachice 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 

 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 



