FROM CHESAPEAKE BAY. 141 



tentacles become elongated but they show no indications of developing other tentacles or of 

 producing ocelli at the bases of the third tentacles. 



Color. The colonies are light brown. 



Bathymetrical distribution. Laminarian zone. 



Development of gonosome. August and September. 



Habitat. Growing in large colonies on Alcyonidium. 



Locality. Hampton Roads, lower parts of Chesapeake Bay. 



Tbe best diagnostic characters of this species are found in the shape of the planoblast 

 and the number of marginal tentacles. All other species of Bougainvillea have primarily 

 but two marginal tentacles in each group. It is very possible of course that the labial 

 tentacles become branched and the marginal tentacles increase in number when they are in 

 a state of nature, but as already remarked they developed no indications of such a change 

 after living in my aquaria for a number of days. The absence of an ocellus from the base 

 of one tentacle of each group is also anomalous. 



Hydractinia echinata Fleming. Plate 9, fig. 40. 



Some of the outer spiles of the wharf at Fort Wool were completely covered from low- 

 water mark to the bottom with a delicate moss-like growth of a milk-white color, which 

 upon close inspection proved to be colonies of this delicate hydroid. I tried in vain to find 

 any mouths to the blastostyles and finding also that the two circlets of tentacles are of quite 

 different lengths, I concluded that they were specimens of H. echinata and not the II. poly- 

 clina of Agassiz, although from their habitat and locality one would expect that they 

 might be the latter. 



I was unable to find any of the capitate, spiral zooids, but found a great many of the 

 simple, tentacular forms described by Wright and Hincks. Among these I noticed one 

 interesting zooid that in its long, slender form was quite like the others, but was provided 

 with an enlarged hollow portion at its distal extremity surmounted by a conical or rounded 

 hypostome and a circlet of tentacles. I was unable to detect any mouth in the hypostome 

 though I spent a number of hours in the attempt. The tentacles were not fully developed ; 

 some of them, five of the nine, being only rudimentary while the other four were a little 

 more than twice the length of the short hypostome and of equal size. 



It is worthy of notice that this form is intermediate between the ordinary tentacular 

 zooid and the normal feeding polypite, and thus offers an explanation of the origin of the 

 tentacular members of the colony. 



From the fact that these forms have been noticed by Wright, Hincks and myself, and 

 from their existing in such considerable numbers in the colonies found at Fort Wool, I am 

 led to believe that the tentacular zooids are regular, normal members of the colony and 

 not abnormal forms as suggested by Allman. 



A peculiar, evidently abnormal form of the feeding polypite I also noticed ; the body 

 was in a greatly swollen condition and remained as represented in figure 40 during 

 the three days that it was under observation. 



1 A Monograph of the Gymnoblastic Hydroids. By J. Allman, F.R.S., etc. Vol. u, p. 346. 



