76 GUIDE TO LOCALITIES. 



among the seaweeds of the beach, between Oak island and the 

 Point of PiDes. This species is especially abundant after an easterly 

 storm, and specimens in good condition may be obtained. It is 

 readily recognized by its long slender form and alternating hydro- 

 thecse. Hydractinia polydina frequently covers the dead shells 

 inhabited by hermit-crabs ; but the specimens obtained on the 

 beach are either dried, showing nothing hut the polyparium, or 

 else the animals are white, an indication that they are dead. Very 

 seldom can living specimens be obtained on the beach. Clava 

 leptostyla may be found attached to Fucus on the rocky portion of 

 the beach, near Crescent Beach station. 



Of bryozoa, the genus Membranipora is represented by several 

 species, encrusting Fucus, Laminaria, or Chondrus crispus. The 

 most common species is M. iiiloxa. Crista eburnea, a small 

 branching form with slender stellate branches, and a coarser form, 

 Cellepora ramulosa, also are common on the seaweed. Other bryo- 

 zoa are to be seen on the cast-up seaweed, and sometimes on stones 

 and shells. 



The only tunicate at all likely to be found on this beach is Bol- 

 tenia rubrum, but this occurs more frequently on Swampscott and 

 Marblehead shores. The normal habitat of this species is in from 

 two to fourteen fathoms of water, where it is attached to rocks or 

 shells . 



SWAMPSCOTT BEACH. 



Route. — By train, Boston and Maine road, from North Union station 

 to Lynn ; fare $ .20. From Lynn via Lynn and Swampscott electrics to the 

 first beach. 



By electrics, from Scollay square, in the Lynn and Swampscott 

 cars; fare $.25, round trip. 



By bicycle, through Chelsea and Lynn to the beach, following car 

 tracks, 15 miles. 



A large number of the species found on Revere beach may be 

 obtained also on Swampscott beach. In addition, a number of 

 others, especially shells, may be found, which are largely derived 

 from the stomachs of fishes cast on the beach by fishermen. One 

 of the most beautiful of these is the small gastropod Margarita 

 obscura. This, although a small shell, is conspicuous from its 

 pearly lustre and iridescence, which appears when the exterior 

 is worn off. Other species of Margarita also occur. Neptunea 

 curia is found more often here than on Revere beach, and perfect 



