502 LONSDALE ON MIOCENE CORALS FROM N. AMERICA. 



The numerical proportions between the large and small open- 

 ings varied greatly, the latter occupying sometimes a considerable 

 part of a limited surface ; but an examination showed that these 

 minor apertures were terminations of young or imperfectly de- 

 veloped tubuli ; every condition, from a minute foramen to a large 

 circular tube, having been observed both on the surface and in 

 sections of the interior ; and in the latter cases small tubuli, repre- 

 sentatives of minute apertures, were noticed gradually attaining, in 

 the range towards the surface, the dimensions of the large circular 

 openings. No indications were detected of a subdivision within a 

 full-grown tube by a vertical plate ranging partly or wholly across 

 it, the mode by which additional polype cavities are chiefly pro- 

 duced in Chcetetes ; but in every instance the young tubuli had 

 been developed in spaces due to divergence, and either occupied 

 them wholly, or were embedded in a pellucid interstitial matter. 

 The original wall of the tubes, where preserved, presented in 

 transverse sections an opaque white circle, strongly contrasted to 

 the surrounding pellucid matter ; and the smallest as well as the 

 largest opening exhibited the same character ; in vertical or 

 oblique sections a similar layer was also sometimes exposed, 

 minutely, but clearly punctured, the pores penetrating likewise 

 into the surrounding interstitial substance. No changes de- 

 pendent upon growth, or upon the cessation of it, were observed. 



In attempting to assign a position in the natural series of Poly- 

 paria to the coral under consideration, it is believed that the 

 characters of the tubuli, the want of internal diaphragms, the 

 structure of the walls, and the mode of developing additional tubes, 

 prove it to belong to the Tubuliporidce of M. Milne Edwards, or 

 the Tubidiporea of M. de Blainville ; and that if it be rightly 

 assigned to Heteropora, the genus should be removed from M. de 

 Blainville's family of 31illepora. 



Localities. — Williamsburg, Petersburg. 



5. ESCHARINA TUMIDULA. (Sp. 11.) 



Cells oblong ; rows radiating, divided longitudinally by a furrow, but not se- 

 parable mechanically ; no transverse furrow between successive cells ; surface 

 slightly convex, with well-defined, large, round pores ; mouth circular, boundary 

 slightly thickened, two small protuberances on the proximal edge, sometimes a 

 small tooth on each side. 



But one condition of growth of this species 

 was noticed, and it is fully represented in the 

 wood-cut. The cells were in general regularly 

 arranged with reference to the individual rows ; 

 but there was no uniformity of disposition as 

 respected the whole surface. Their length was 

 about one fourth of a line, and breadth one 

 sixth. The interpolated or additional series 

 sprung from the side of an oral termination ; 

 but from their mode of insertion, they might 

 be considered as having had an independent mcharina tumMuia. 

 origin, or having been developed from gem- 



[Greatly magnified.] 



