NO. 19.] ECHINODERMS OF CONNECTICUT. 17 



as to the relationships of the present-day Echinoderms, supported 

 by an abundance of paleontological material, furnishes one of 

 the best proofs of evolution. 



Specimens of all classes of Echinoderms may be preserved in 

 80 per-cent alcohol. Formalin should not be used unless abso- 

 lutely necessary, and should then be replaced by alcohol as soon 

 as possible. Starfishes, serpent stars, and sea-urchins may be 

 narcotized by adding magnesium sulphate (Epsom salts) to the 

 sea water in which they are placed, and then killed by short 

 immersion in fresh water or weak alcohol. They should then 

 be placed in 50 to 70 per-cent alcohol for a few hours, and 

 afterward preserved in 80 per-cent alcohol. For the preserva- 

 tion of holothurians with their tentacles expanded, it may be nec- 

 essary to add the magnesium sulphate to the sea water very 

 gradually. Otherwise the animals may contract vigorously. 



Starfishes, ophiuroids, and echinoids make useful specimens 

 when carefully dried. But all such specimens should be killed 

 as indicated and placed for a day or two in strong alcohol. They 

 should then be dried thoroughly by artificial heat. To prevent 

 future injury from insect pests it is desirable to add a very minute 

 quantity of corrosive sublimate to the alcohol in which the spec- 

 imens to be dried are first preserved. It must be remembered 

 that corrosive sublimate is a most powerful poison and must be 

 handled with very great care. 



The general scope of this report does not admit of an ex- 

 tended account of the internal structure of the various species 

 included. For those who desire to make a thorough study of 

 the organs of the body cavity of these animals the detailed de- 

 scriptions given in various handbooks and laboratory guides in 

 zoology are available. In the following chapters, therefore, will 

 be given only such descriptions of the external . features and 

 internal organs as are necessary for an understanding of the 

 relationship of the various groups, their natural history, includ- 

 ing habits and life history of the various species, and for the 

 accurate determination of each species. 



Under the description of the species, only those characters 

 which serve to distinguish our native species or have a direct 

 bearing on their mode of life will be mentioned. More detailed 

 anatomical descriptions of most of the species may be found in 



