FOKMS OF THE SPEEMATOZOA. 143 



Sternaspis possesses short spermatozoa that are pointed at one 

 end. In the Earthworm the spermatozoa are somewhat 

 thickened at one end, and in Branchiobdella they are very 

 much attenuated, and spirally coiled at one extremity (v. 

 Siebold). 



In the ANNELIDA spermatozoa are found with spheroidal or 

 pyriform heads and attenuated body : Phyllodoce, Syllis, (Ehlers, 

 Keferstein). 



ARTHROPODA. The seminal animalcules of the Arthropoda 

 are of especial interest in consequence of their diversity of 

 structure. Thus Ley dig describes the spermatozoa of Noto- 

 mata Sieboldii to be sickle-shaped bodies with nucleus and 

 nucleolus, and an undulating membrane at one border. He 

 likewise observed thick rod-like bodies with a central thicken- 

 ing. Two forms of spermatozoa are consequently here present 

 in the same individual. 



The CIRRIPEDIA, as Balanus and Lepas, possess also sim- 

 ple capilliform spermatozoa (v. Siebold, Kolliker). Frey and 

 Leuckart describe the spermatozoa of Caligus as egg-shaped 

 bodies having the genetic significance of nuclei. In Cyclops 

 quadricornis, according to Zenker, they are rod-shaped with 

 two coils ; in Cyclopsine, according to v. Siebold, they are of 

 oval form. 



The spermatozoa of OSTRACODA, according to the statements 

 of Zenker and Metschnikow, possess a very remarkable and 

 highly complex form. In Cypris ovum they are three times 

 the length of the entire animal, and have the form of a coiled 

 rod, bordered lengthwise by a spiral plate. A similar anoma- 

 lous form is exhibited by the spermatozoa of Cythere viridis. 

 According to Zenker, these are provided with a lash having 

 one broad abrupt extremity, and a more pointed one to which 

 a pedicle is attached at right angles, that appears to be twisted 

 like a ribbon round its axis. Argulus, according to the obser- 

 vations of Leydig, possesses spermatozoa, whilst the seminal 

 corpuscles of the PHYLLOPODA (Artemia, Branchipus) he ex- 

 amined were cellular in form. They appear to be vesicular 

 structures, with a diameter of 3ju, and marked with clear spots. 

 The seminal corpuscles of the Daphnidce are described by 

 Leydig as being usually small rod-like corpuscles ; in a few 



