46 bulletin: museum of comparative zoology. 



STAURODISCUS, Haeckel, 1879. 

 Staiirodiscus tetrastaurus, Haeckel. 



Figs. 47-49, Plates 18, 19. 



Staurodiscus tetrastaurus, Haeckel, E., 1879, Sj'st. der Medusen, p. 145, Taf. IX. 

 rigs. 1-3. 



Specific Characters. — The bell is 4,5 mm. in diameter, and about twice as 

 wide as it is high. In adult medusae there are 8 long flexible tentacles with 

 hollow basal bulbs. In some specimens there are 24, and in others 16 sensory 

 clubs upon the bell margin. There are always 32 black entodermal ocelli, 

 one at the base of each tejitacle bulb and sensory club. The velum is well 

 developed. Only 4 radial canals reach the circular vessel. Each of these 

 canals gives rise to a pair of side branches that end blindly. The gonads are 

 situated upon these side branches and upon the distal portion of each radial 

 canal. The proboscis bears 4 prominent lips. The color of the entoderm of 

 this medusa is green or yellow. 



In the youngest specimen observed, the bell was 1 mm. in diameter and 

 about as high as it was broad. There were 4 well-developed tentacles, 4 rudi- 

 mentary tentacle bulbs, and 8 marginal clubs (see Figure 47, Plate 18). The 

 medusa was very common at the Tortugas, Florida, in July and August, 1898. 

 Haeckel, 1879, found this species in the Canary Islands, at Lanzerote. 



TETRACANNOTA, nov. gen. 

 Tetracannota coUapsa, nov. sp. 



Figs. 14-16, Plates 7, 8. 



Generic Characters. — Tetracannota is closely allied to Cannota and Bere- 

 nice. It may be defined as having 16 radial canals, which in the adult become 

 arranged in 4 groups, each group consisting of 4 canals. Gonads 16 in num- 

 ber, and situated upon the distal regions of the radial canals. An entodermal 

 pigment spot at the base of each tentacle. No otocysts. Tentacles numerous. 



Specific Characters. — Adult medusa; Figure 14. The bell is 7 mm. in 

 diameter, and about as high as it is broad. The top is dome-shaped, and the 

 side walls are vertical. There are 16 well-developed tentacles that are carried 

 tightly coiled in close helices. In addition to these there are 112 very small, 

 rudimentary tentacles. Dark-brown entodermal pigment is found at the base 

 of each tentacle. There are 16 radial canals, arranged in 4 groups of 4 each. 

 The gonads are found in the proximal portions of the 16 radial canals very 

 near to the point where they branch off from the proboscis. The peduncle of 

 the proboscis is wide and prominent. The proboscis possesses 8 slightly crenu- 



