54 THE MEDUSAE. 



This species is widely distributed, having been recorded from the eastern 

 coast of North America (McCrady, '57^ Brooks, '86), the Gulf of Mexico 

 (Mayer, : 00''), the Malay Archipelago (Maas, : 05), the Fiji Islands (Agassiz 

 and Mayer, '99), and from the west coast of Mexico by the present 

 expedition. 



Cunoctantha tenella, sp. nov. 

 Plate 15, Fig. ^ Type; Plate 16, Fig. 2; Plate 17, Figs. 6, 7. 



Acapulco Harbor, surface. Many specimens, 2-7 mm. in diameter. 



The bell in a specimen 5 mm. in diameter is 3.5 mm. high, its surface 

 smooth. The marginal zone and lappets are very narrow and but slightly 

 incised in the radii of the tentacles. The peroniae are correspondingly short, 

 and consist chiefly of kidney-shaped nematocyst pads underlying the bases of 

 the tentacles, such as occur in C. odonaria and Ciinina peregrina. These struc- 

 tures have been described and figured in detail for C. odonaria by Wilson ('87). 

 There are eight tentacles in every specimen whether small or large, good 

 evidence that this is the typical number, and that the species belongs to the 

 genus Cunoctantha, not to Cunina. In the larger specimens there are three 

 otocysts per lappet; in the smallest, however, 2 mm. in diameter, there is 

 only one in each lappet (PI. 16, fig. 2). No lappet in any specimen bore 

 more than three, but inasmuch as it is doubtful whether any of them had 

 reached their extreme size it is possible that more might be developed. The 

 sense organs themselves (PI. 17, fig. 7) closely resemble those of C. odonaria, 

 containing, like the latter, one or two otocysts, and being situated on low 

 prominences of the nerve ring. Each otocyst is connected with a short 

 otoporp, although in the present species these do not form such prominent 

 ridges as they do in C. odonaria. 



C. tenella is interesting chiefly for the fact that while in the number 

 of its tentacles, gastric pockets, and marginal lappets it is a typical Cunoc- 

 tantha, it yet exhibits a well-developed peripheral canal system, a feature 

 entirely lacking in the two species of this genus previously known. The 

 peronial canals are very short, corresponding to the short peroniae ; but they 

 and the festoon canal are both rather broad (PI. 17, fig. 7). The central 

 stomach also shows an interesting feature in that the gastric pockets, instead 

 of being nearly rectangular, as in most other members of the Cunanthidae, 

 are almost triangular, as is shown in the general sketch of the Medusa 

 (PI. 15, fig. ^). This form of the pockets is to be seen even in the smallest 



