246 



FIELD. 



[Vol. XI, 



A. Head.^ 



[■ Head proper. 



Nucleus. 

 Centrosome. 



Mitosome. | The so-called " Nebenkern," " middle piece," 



l^Cell membrane. S " corpuscle accessoire," etc. 

 Probably also surrounding the head, and within the cell mem- 

 brane a minute quantity of cytoplasm. 



B. Tail. 



Table of Measurements of Constituent Parts of Spermatozoa of the 

 Species of Echinoderms Studied. 



Holothurioidea 



Echinoidea 



Crinoidea 



Antedon rosacea 



Ophiuroidea . 



Asteroidea 



o.. u T \ longitudinal 



Stichopus regalis \ * 



( transverse 



TT 1 ^1. • Ti 1- i longitudinal 

 . Holothuria Poll •,' ^ 

 ^ I transverse 



Cucumaria \ longitudinal 



cucumis I transverse 



cEchinocardium \ longitudinal 



cordatum ! transverse 



Echinus microtu- \ longitudinal 



berculatus ! transverse 



Spaerechinus \ longitudinal 



granularis ' transverse 



Strongylocentro- ( longitudinal 



tus lividus ( transverse 



. , . , , ( longitudinal 



Arbacia pustulosa ; ° 



( transverse 



\ longitudinal 



( transverse 



Ophioglypha \ longitudinal 



lacetosa ' transverse 



Ophiomyxa ( longitudinal 



pentagona ( transverse 



Ophiothrix fragilis < °^ 



I transverse 



Ophioderma \ longitudinal 



longicauda ( transverse 



'Chaetaster \ 



, ■) longitudinal 



longipes ' ° 



Astropecten pen- ( longitudinal 



tacanthus ( transverse 



, . ,. ( longitudinal 

 Asterias giaciahs < ° 



( transverse 



Echinaster ( longitudinal 



sepositus ( transverse 



, ^ . „ , .. ( longitudinal 

 Asterias Forbsii < " 



I transverse 



