LEPTOMEDUaSi — OCTOCANNA, OC'TOGONADE. 



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bulbs, except small ones destined to develop into large tentacles (Maas). Browne, however, 

 describes rudimentary tentacle-bulbs 3 to 4 times as numerous as the tentacles. The 

 lithocysts are somewhat more numerous than the tentacles and are situated upon the bell- 

 margin, one or two being found between each successive pair of tentacles. Each lithocyst 

 usually contains 2 concretions, rarely 1 or 3. There are 8 straight, narrow radial-canals and 

 a simple, slender ring-canal. Stomach large, 8-sided, and the 8 radial-canals extend inward as 8 

 grooves in the floor of the stomach and meet at the center. There are 8 small lips. The 8 

 gonads are spindle-shaped with blunt outer ends. They begin in the middle third of the radial- 

 canals and extend almost to the end of the radial-canals near the ring-canal. 



The medusa is colorless. The preserved specimens studied by Maas exhibited a light 

 brownish-green hue in their entodermal parts. 



This medusa is found in the Malay Archipelago and off" Ceylon. Browne gives a clear 

 figure and description based upon 3 specimens from Ceylon and the Gulf ot Manaar; and 

 Maas gives a good account of specimens from New Guinea and the Malay Archipelago. 



Fig. 180. — Octogonade mcditerranea, after Zoja, showing one of the marginal sense-organs. 



Fig. 181. — Stomobrachium tenlaculalum, after A. Agassiz, in North American Acalepha?. Side view of the medusa. 



Fig. 182. — Stomobrachium lentaculatum, oral view, after A. Agassiz, in North American Acalepha?. 



Bigelow, 1909, describes a quite similar medusa from Acapulco Harbor, Pacific coast of 

 Mexico, but the gelatinous substance is very thick, the bell being 10 mm. high and 8 mm. 

 wide with a very shallow bell-cavity, thus resembling a specimen referred to 0. polynema by 

 Browne. Bigelow's medusae had only 8 large radial tentacles and 8 to 24 marginal bulbs, all 

 bearing excretory papillae. 8 mature gonads. Bigelow's medusae may be a variety of 0. 

 polynema, but the differences between them and the typical form are so marked that we may 

 be obliged to consider them as being specifically distinct. 



Genus OCTOGONADE Zoja, 1896. 



Octogonade, Zoja- 1896, Bolletino Scientif. Pavia, anno 17, p. 101. 



The type species and only known form is O. mediterranca Zoja, from Messina, Sicily. 



GENERIC CHARACTERS. 



iEquoridae with 8 simple radial-canals arising separately, 45° apart, from the periphery 

 of the stomach. Numerous lithocysts each with 12 to 20 concretions and an ocellus. Numer- 

 ous tentacles. 8 lips. No peduncle. 



The marginal sense-organs appear to resemble those of Tiaropsis. The genus Octo- 

 gonade is distinguished from Octocanna solely by its marginal ocelli. 



