bulletin: museum of comparative zoology. 



OCTONEMA, Haeckel, 1879. { 



i 

 Octonema gelatinosa, nov. sp. 



Figs. 20, 31, Plate 6. 



Specific Characters. — Yovmg medusa? The bell is 3.5 mm. in diameter 

 and somewhat flatter than a hemisphere. The gelatinous substance is quite 

 thick. In the single specimen examined there were 4 tentacles with long 

 hollow basal bulbs. These tentacles were about 2 times as long as the bell 

 diameter. Within the entoderm of the inner side of each tentacle bulb there 

 was a single dark-colored pigment spot. In addition to these long tentacles 

 there were 12 rudimentary tentacle bulbs upon the bell margin. It is possible 

 that these might have in time developed tentacles ; in the specimen observed 

 by us, however, they were very small and apparently rudimentary. A dark- 

 colored pigment spot was found in the entoderm of each of these tentacle bulbs. 

 There were 8 marginal clubs, 2 in each quadrant. A dark-lirown entodermal 

 pigment spot was situated at the base of each (see Figure 21). The velum was 

 well developed. There were 4 straight radial canals upon the upper regions 

 of which the gonads were situated. The proboscis was a simple tube with 4 

 simple lips. The color of the entoderm of the 4 large tentacle bulbs, and of 

 the radial tubes in the region of the gonads was green. 



A single specimen was found in Charleston Harbor, South Carolina, 

 September 14, 1897. 



ORCHISTOMA, Haeckel, 1879. 

 Orchistoma tentaculata, nov. sp. 



Fig. 19, Plate 5. 



Sjyecific Cliaracters. — Young medusa : The bell was 6 mm. in height. The 

 sides near the margin were slightly flanged outward. The gelatinous substance 

 of the upper portion of the bell was very thick, so that the concavity was 

 shallow. There were thirty-two marginal tentacles in various stages of devel- 

 opment, the longest being about 1.5 times as long as the bell height. The tenta- 

 cles possessed long, hollow basal bulbs. There were no marginal sense-organs. 

 There were sixteen functional radial tubes, and sixteen others in process of 

 development. The radial tubes were straight, and there were no traces of 

 gonads upon them. The velum was well developed. The proboscis was flat 

 and shallow, and there were 8 lips. The entoderm of the basal bulbs of 

 the tentacles was of a delicate green. Only one immature specimen of this 

 medusa has ever been seen ; it was found at Newport, Rhode Island, August 

 18, 1896. The genus is closely related to Melicertum. 



