584 DR J. STUART THOMSON ON 



The following measurements of the two specimens may be noted : 



The surface of the " pileus " shows numerous large autozooids, between which the 

 still more abundant but much smaller siphonozooids are situated. The autozooids in the 

 large specimen are over a hundred in number, and surrounding each of these are the 

 minute siphonozooids. The diameter of a contracted autozooid is on an average 2-3 

 mm., that of a siphonozooid 1 mm. 



Between the adjacent walls of two autozooids, there are about twenty siphonozooids, 

 but this number naturally varies considerably. The specimens showed autozooids in 

 very varied degrees of expansion, from those with well-expanded tentacles and pinnules 

 to those simply consisting of an eight-partite swelling on the surface of the 

 coenenchyma. 



In the expanded autozooids the external layers are fairly transparent, and thus the 

 pink-coloured stomodasal canal and yellowish mesenterial filaments are seen through the 

 transparency. Thus, even externally, one can distinguish (a) a crown with eight 

 tentacles, each provided with eleven pairs of pinnules, (b) a long, extended, stomodseal 

 part, and (c) a part containing the mesenterial filaments. 



The following measurements of a well-expanded autozooid may be noted : 



Height of expansion of autozooid above surface of coenenchyma, 10 mm. 



Height of crown and tentacles, . . . . . 2'0 



Diameter of spread of tentacles, . . . . . 4'0 ,, 



Length of tentacle, . . . . . . 0'510 ,, 



Breadth of tentacle, including pinnule, . . . . T190 ., 



Length of pinnule, . . . . . 0'170 ,, 



Breadth of pinnule, . . . . approximately the same. 



Approximate length of stomodseal part, . . . . 2'0 mm. 



Approximate length of part containing the mesenterial filaments, 6'0 ,, 



Breadth of the latter, . . . . "". 5'0 ,, 



These dimensions probably vary considerably in different autozooids, according to 

 the degree of expansion. 



