NORTH AMERICAN EARLY TERTIARY BRYOZOA. 453 



OCHETOSELLA ROBUSTA, new species. 



Plate 57, figs. 11-17. 



Description. The zoarium is free, cylindrical, branching. The zooecia are 

 large, elongated, cylindrical; the frontal is very convex: it is terminated distally 

 by a salient and almost complete peristomie ; it is formed of a tremocyst with very 

 small pores. The oral mucro bears a trenched spiramen and avicularium; the 

 peristomice is very oblique; its outlines are undefined. The oral avicularium is 

 round, simple and without pivot. 



(2=1.20-1.30 mm. 

 Measurements. Zooecia , __,, 



U2=0.6o mm. 



Variations. The development of the calcification gives to the zooecia some 

 quite variable aspects which it is impossible to analyze, but which figures 14 to 17 rep- 

 resent sufficiently. Figure 12 represents a very curious case of an inversion of 

 zooecia on the same branch. 



Affinities. This species is always easy to distinguish from Ochetosella jack- 

 sonica by its large branches and the absence of areolae. 



Occurrence. Middle Jacksonian: Wilmington, North Carolina (common); 

 near Lenuds Ferry, South Carolina (rare). 



Cotypes.G&t. No. 64122, TJ.S.N.M. 



Family SMITTINIDAE Levinsen, 1909. 



Anatomical bibliography. 1SG5, SMITT, Skandinaviens Hafs-bryozoer, Ofversigt Kongl. Vet- 

 enskaps-Akademieus Forhandlinger, vol. 22, pi. 3, figs. 9, 10, 11; pi. 5. fig. 4. 1892. WATERS, 

 Observations on the Gland-like Bodies in the Bryozoa, Journal Linnean Society, London, 

 Zoology, vol. 24, pi. 19, figs. 15, 16. 1900. WATERS, Bryozoa from Franz Joseph Land, pi. 10, 

 figs. S-17; pi. 12, figs. 3, 4. 1904. WATERS. Expedition Antarctic Beige, Bryozoa, pi. 4, 

 figs. 1, 2. 1909. WATERS. Reports on the Marine Biology of the Sudanese Red Sea. XIII. 

 The Bryozoa, Journal Linnean Society, Lo ndon, vol. 31, pi. 14, fig. 14 ; pi. 15, fig. 11. 



The ovicell which is hyperstomial and imbedded in the distal zooecia opens 

 into the peristomie. The peristome is produced and channeled in front. The 

 operculum is (not universally) very thin; the lower edge is straight or slightly 

 curved inward and hardly separated from the ectocyst; the muscular attachments 

 are usually a ridge on the border. There are very small oral glands often partly 

 attached to the tentacular sheath. Spines. 



This family is a very important one, but unfortunately our knowledge of the 

 anatomy and embryology is too little to allow us to fix its exact limits. The de- 

 velopment of the peristome is one of the essential characters; we continue to follow 

 the same terminology as for the preceding families. The orifice of the peristome is 

 the peristomice (secondary orifice of Hincks) ; it is irregular and its outlines are 

 vague and undefined. The apertura is the zooecial orifice closed by the operculum ; 

 it is not always visible externally. The internal tube formed by the development 

 of the peristome is the peristomie. 



The calcification functions as in other genera. Nevertheless, the pleurocyst is 

 a frequent occurrence, and the greater part of the time the two calcareous layers 

 are separable. 



