HYDROIDS OF WOODS HOLE. 



383 



distinguishable. Hence such organs as tentacles, gonophores, 

 etc., which afford important specific characters, were wholly 

 lacking. I had at first attributed this condition to bad preserva- 

 tion ; but collections made at two subsequent seasons, in each 

 case care being taken to preserve by approved methods, have 

 convinced me to the contrary. It seems highly probable that 

 this hydroid during the summer season is in a state of suspended 

 animation, so to speak ; a condition quite common among hy- 

 droids at various seasons. It must suffice in this connection to 

 make brief reference to a few features, as hydrothecae, etc. As 

 shown in the figure, the hydrothecae are tubular structures, aris- 

 ing from the axial tubes by rather narrow necks, and extending 



FIG. 10. Cross-section of stem. I, Axial tubes ; 2, hydrothecse ; 

 3, coenosarcal strands. 



upward and outward, becoming more or less curved, and open- 

 ing to the surface by somewhat oblique mouths. While in many 

 cases there seemed to be opercular-like folds at the thecal open- 

 ings yet they were difficult to definitely demonstrate or describe. 

 As to size hydrothecae averaged about 0.7 to I mm. in length, 

 by about 0.12 mm. in diameter at median portion, somewhat 

 larger at mouth. In no case were gonangia distinguishable, nor 

 evidences of germ cells. This might be expected as to the last, 

 but if gonangia are an organic part of the skeleton one might 



