1)8 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



the ripe sperm sacs of the males which are 

 always milky white in colour, and can therefore be 

 readily distinguished from the ova, discharge great 

 quantities of spermatozoa into the body cavity, and thence 

 by way of the mouth into the water. Fertilisation is 

 most probably effected in the water, and not in the body 

 cavity of the female just before the discharge of the ova. 

 If this is the case, the sexual act is a true process of 

 spawning. 



The exact time of spawning may vary in different 

 localities. In the Plymouth district I have found, as a 

 result of a six years' series of observations, that the 

 spawning always occurs during the last fortnight in 

 December and the first fortnight in January, and at no 

 other time of the year. At Port Erin the spawning may 

 be somewhat later, as I have examined larvae captured 

 with the Plankton at Easter, which I feel certain are the 

 larvae of Alcyonium digitatum. 



Anatomy of the Colony. 



When a colony of Alcyonium is cut across (Plate I., 

 fig. 5) it will be seen to consist mainly of a number of 

 parallel tubes perforating a semi-transparent gelatinous 

 substance in which a number of small calcareous spicules 

 are imbedded. Each of these tubes is the body cavity — 

 or coelenteron — of a polyp, and the gelatinous substance 

 is the mesogloea of the polyps fused together into a 

 common mass. 



When the colony is alive and in a healthy condition 

 a number of delicate transparent polyp heads protrude 

 from the surface of the colony. Each of these is provided 

 with a mouth and eight pinnate tentacles, and the body- 

 wall below the crown of tentacles encloses a single large 

 cavitv, which is continuous with the cavity of the tubes 



