belonyiiKj to the Family LaodiceidcC. 463 



found in the North Atlantic and Mediterranean, one finds 

 that between every two tentacles there are always one 

 cordylus (rarely two) and either one or two cirri. Tiie ocelli 

 are variable in number and not quite constant in position, 

 and their colour is variable — dark brown, dark violet, or 

 black. The colour of gonads and other organs is also vari- 

 able — dark yellow, brown, pink, or pale violet. The tentacles 

 are numerous and have, when fully developed, an endodermal 

 basal spur, which is variable in length and shape. The 

 gonads, when mature, form undulating bands upon the radial 

 canals. 



Distribution. North Atlantic ; Europe, British coasts 

 (L. undulata, Forbes and Goodsir ; L. calcarata, Browne). 



Mediterranean (L. mediterranea, Gegenbaur ; L. cruciata, 

 Ma as). 



Canary Is. {L. uJothrix, Hasckel). 



Bahamas {L. idothria:^ Mayer). 



North Atlantic ; American coast (Z>. calcarata, Agassiz, 

 Brooks, Hargitt). 



Tortugas, off Florida {L. ulothrtx, Mayer). 



The Ilydroids belonging to Laodice calcarata and 

 Laodice undulata. 



A. Agassiz (1865, p. 124) gives a brief descri{)tion with a 

 figure of the hydroid which he believed to belong to Laodice 

 calcarata. It is necessary, however, to criticize this con- 

 nexion of the hydroid with the medusa, as it is a matter of 

 some importance. 



Agassiz discovered a small hydroid which he considered 

 to belong to the genus Lafoea, hence the ntxmG La/oea calcarata. 

 The hydroid is a small creeping form and was found just 

 below low-tide mark in Buzzard's Bay, Naushon. The 

 hydranths are arranged " in a quincunx manner on both sides 

 of a long slender creeping stolon, which does not branch." 

 The figure shows that the perisarc is tube-like, and there is 

 no evidence of an operculum. The hydroid has a few very 

 large gonothecK, inside of which develoj) medusa. The 

 medusa on liberation has " two long tentacles, tM'o slightly 

 developed ones, and four more hardly ])erceptible in the 

 middle of the space between the chymifcrous tubes (radial 

 canals)." Tlie basal bulbs of the two tentacles and the other 

 six tentacular buds each have one dark pigment-spot. This 

 medusa on liberation from its hydroid has only two long 

 tentacles, no cirri, and no cordyli. 



The next stage mentioned is much older than the earliest 



