﻿Dec, 1857.] 



ELLIOTT SOCIETY. 



255 



In form, this species appears to me to differ from B. alata, 

 Agassiz, by its greater height in proportion to its width, and, 

 consequently, by the less expanse of its wing-like lobes. In 

 generic type, it seems identical with that species. 



In the month of May, I had several full-grown specimens of 

 this species in my jars, and a few small Cydippe-like Medusae, 

 taken at the same time. After the lapse of a few days, the 

 Medusae remaining still very active and lively, I found the number 

 of these Cydippe-like individuals decidedly increased ; at the 

 same time, appeared in the jar, a number of minute, ciliated ani- 

 mals, barely visible to the naked eye. These were submitted to 

 the microscope, and appeared as represented in ff. 1, 2 and 3, PI. 

 14, young and very small, Cydippe-like Medusae, still smaller 

 than those easily observed ones, also like Cydippe, which were 

 taken with the full-grown Bolinas. One of these measured about 

 .06 inch, in length, by about .45 inch, in greatest breadth. 

 The profile outline was somewhat pyriform. The mouth occupy 

 ing the less rounded extremity was proportionately large, and 

 opened into a digestive cavity of elongated funnel-shape, tapering 

 as it receded from the mouth. Above at its apex this cavity com- 

 municated with a rudimentary circulatory system, consisting of 

 two broad sinuses, one on each side of the narrow transverse mid- 

 dle portion into which the digestive cavity opened. Each of these 

 sinuses corresponds with the main trunk and its four horizontal 

 branches in adult forms. Each of them, even at this stage, had 

 on its outer side, four short pointed projections, corresponding to 

 the four horizontal branches in the adult, and distributed like 

 them to each of the four rudimentary ambulacra, as represented 

 in fig. 3, 4. There were, as in the adult Medusas, eight ambu- 

 lacra, but these were very short, as represented in ff. 1, 2, 

 containing each only from five to seven transversely arranged 

 ciliary combs. These short ambulacra are very narrow, and are 

 arranged in pairs two and two, and have not the equi-distant aspect 

 presented by the same structures in the adult. The short pointed 

 representatives of the radiate tubes, which pass off from the great 

 lateral sinuses to the ambulacra, meet the latter rather low down, 

 the greater portion of the ambulacrum apparently lying above 

 them. The ambulacral or superficial vessels appeared to exist at 

 this stage, but not to descend below the short ambulacrum ; in the 

 whole space between the lower extremities of the short ambulacra 

 and the mouth, there was not the smallest trace of a vessel of any 



