626 



YAICHIRÔ OKADA : 



Ortmann ranged this species under Busk's Reteporella. In agree- 

 ment with Waters I greatly doubt the tenability of Reteporella as a 

 genus distinct from Retepora. Sufficiently warranted as seems to me 

 the amalgamation of the two, yet the former may possibly be held up 

 as a subgenus under the latter. In addition to the non-reticulate 

 character of zoaruim in all the species which had been taken under 

 Reteporella, there may exist some more common characters by which 

 that group as a subgenus might be distinguished from Retepora s. str. 

 At least in all the four species studied by me and with non-reticulate 

 zoarium — viz., Retepora (Reteporella) minor (Ortm.), R. kinoshitai n. 

 sp., and R. crennlata n. sp. — I find, as against Retepora s. str., /) the 

 ovicells are immersed, not raised ; 2) their ventral wall is prolonged 

 below into a sort of lamina extending a certain distance into the 

 zooecial aperture ; j) the aperture of ovicell is longitudinally fissure- 

 ilike with non-denticulate margin ; 4) the avicularian gland is single 

 globular, and usually larger in ventral, than in vicarious avicularia. 



13. Retepora crenulata, n. sp. 

 Pl. VIII., fig. 6; textfig. 5. 



Zoarium erect, about 50 mm. high, consisting of dichotomously 

 subdividing branches which expands fan-like or are somewhat con- 

 torted. The branches are somewhat flattened dorsoventrally, almost 

 truncate at end, and nearly uniformly wide throughout. Zooecia 

 (textfig. 5 a-b) mostly rhomboidal, not infrequently oval, arranged 

 in alternating rows ; surface distinctly nodulous except along lower 

 margin of zooecial aperture which is smooth, frequently perforated by 

 minute, irregularly scattered pores. In young zooecia (/z) at the end 

 of branches, the distal parts of zooecium are distinctly prolonged in a 

 tubular manner. Zooecial aperture circular, with raised and serrated 

 lower margin which shows a small labial fissure in the middle ; the 

 upper margin is entire in mature zooecium, while in young zooecia 

 it is 4-5 -toothed, the teeth being moderately prominent and frequently 



