212 ECHINODERMATA 



Order 1. Elasipoda. 



Well-marked bilateral symmetry. Tube feet 



on ventral and papillae on dorsal surface. 



Deep sea only. 

 Order 2. Pedata. 



Ambulacral feet in rows or scattered. (Thy- 



one, Cucumaria.) 

 Order 3. Apoda. 



Without tube feet. Wormlike. (Synaptula.) 



Class 5. Crinoidea. 



Temporarily or permanently attached by a 

 stalk. With five branching arms radiating 

 from a small disk. 

 Order 1. Neocrinoidea. 



Characters as above. (Antedon, Pentacrinus.) 



Berry : Metamorphosis of Echinoderms. Quart. Jour. Mic. Sci., 38, 1905. 

 Coe: Echinoderms of Connecticut. State Geol. and Nat. Hist. Surv., 



19, 1912. 

 Grave: Occurrence among Echinoderms of Larvae with Cilia Arranged 



in Transverse Rings. Biol. Bull., 5, 1903. 

 Newman, H. H.: Experimental Analysis of Asymmetry in Starfish— 



Patiria miniata. Biol. Bull., vol. 49. 



ASTEROIDEA 



ASTERIAS (Starfish) 



Starfishes are rather common along most coasts and are 

 among the worst enemies of oysters, mussels, clams, and bar- 

 nacles. They occasionally capture fish in aquaria. They 

 can generally be most satisfactorily examined on shallow- 

 water mussel-beds or on rocks covered with barnacles. 

 Places where starfish occur should be visited, and the con- 

 ditions under which they live studied. 



1. How do they feed? 



2. What enemies do they have? 



3. How are their arms repaired when injured? Do you 

 find specimens that are growing new tips to injured arms or 

 are such arms apparently replaced? When an arm is injured 

 how must the animal proceed to repair it? 



4. Do specimens ever conceal themselves? See if speci- 



