74 



GUIDE TO LOCALITIES. 



most of these will be found dead. The most common crab is the 

 cosmopolitan Cancer irroratus, which is found both dead and in a 

 living state. It is most abundant among the rocks and in the 

 rocky pools. The horse-shoe crab, Limulus polyphemus, is not 

 common on the Revere shore ; although the exoskeletons and dead 

 animals, as well as living ones, are cast up occasionally on the beach, 

 or stranded by the retreating tide. It is seldom that good speci- 

 mens can be obtained, these being far more common on the flats 

 and marshy lands in the southern part of Massachusetts bay, and 

 still more so on the South and Cape Cod shores. Occasionally the 

 animals may be seen swimming below low-water mark on the 

 Revere shore. Among the cirrhipeds several species of goose 

 barnacle, Lepas, and the acorn barnacle, Balanus balanoides, are 

 common, the latter encrusting stones on the stonier portion of the 

 beach. 



Of nemertean worms, Meckelia ingens^ may be obtained opposite 

 Oak island station, in muddy sand one to two feet below low-water 

 mark. In the same place the polychaete worm Nereis virens 

 occurs, at a similar depth below low water. With it live several 

 species of Rhynchobolus. In the muddy sand on Saugus river at 

 the northern end of the beach, and a little beyond the Point of 

 Pines station, several polychsetes may be found by digging. 

 Among these are CUmanella torquata, which constructs long round 

 tubes of agglutinated sand, and Rhynchobolus americanus. With 

 these worms occurs the holothurian Leptosynapta girardii, usually 

 in considerable numbers. The sedentary worms are represented 

 by several species of Spirorbis, which are found in abundance 

 attached to seaweeds cast up on the beach by storms. The 

 animals frequently may be obtained alive just after they have been 

 cast up. 



Echinoderms are not very common on the beach. Small star- 

 fish, Asterias, may be found commonly among the roots of Lamina- 

 ria where small sea urchins, Strongylocentrotus, and brittle stars, 

 Ophiopholis, also occur. The sea urchins are found also in a more 

 or less battered condition among the seaweed after storms. The 

 sand dollar Echinarachnius jMrma rarely is found on this beach. 

 Two species of holothuriaus also may be found on the beach 

 after storms. Of these, Caudina arenata often occurs in great 



1 For notes upon this and the following worms, I am indebted to the Zoological 

 Department of Harvard College. 



