BRYOZOA OF WOODS HOLE REGION. 245 



The cell shows a great amount of variation from the young to the adult, depending on the amount 

 of calcification, and when the ooecia are plentifully developed the general appearance of the colony is 

 much changed. The front of one cell often overlaps the base of the one anterior to it, especially when 

 the cells are crowded. A transverse bar is occasionally developed on the top of the rostrum (var. 

 cristata Hincks). The secondary calcined layer covering up the costae, common in northern specimens, 

 is seldom developed in this region and I have seen the large, pointed avicularia, described by Hincks, 

 only rarely in specimens from this region. 



Taken at Crab Ledge, where it is common in 14 to 20 fathoms, and at Great Round Shoal in 8 

 fathoms, where it is scarce. A specimen in Verrill's collection is labeled " Discopora scabra, Nan- 

 tucket Shoals." The species ranges northward to the Arctic Ocean. 



Rhamphostomella ovata (Smitt). [PI. xxvi, fig. 63, 633.] 



Smitt 1867, p. 31 (Cellepora ovata). 



Verrill iSygb, p. 19;, and 18790 (Mucronella ovata). 



Whiteaves 1901, p. 108. 



Zoarium encrusting stones and shells. Zooecia large, slightly convex, with large punctures and 

 a series of marginal areolae, between which arise strong costse running only a short distance toward the 

 center; in older cells the punctures and areolae are more or less closed over; orifice large, ovate (or sub- 

 circular), with the pointed end posterior, the median tooth wanting; peristome slightly raised, and 

 behind the orifice and a little to one side, developed in connection with the peristome, a strong, blunt, 

 smooth rostrum which bears an oval avicularium on its median side. Ooecia subglobular, prominent, 

 smooth, imperforate or very finely punctured, sometimes with a single median pore. 



Rare in this region, but occurs occasionally at Crab Ledge in 14 to 20 fathoms. I have seen one 

 specimen from Vineyard Sound, a single colony in the United States National Museum collection, 

 taken in 1875 at station 4708, and others in the same collection from Nantucket Shoals. The species 

 is a northern one and has been reported only from Canadian waters. 



Genus SMITTIA Hincks, 1879. 



In this genus the presence of a tooth or shelf-like protection on the posterior margin of the zooecial 

 orifice is usually distinctive, but it is not possible to draw the limits sharply. The tooth may occasion- 

 ally be wanting, as in S. porifera; again the shelf is present in Porella concinna, a species which 

 Jullien and Calvet place in the genus Smittia on this account, but which has generally been placed 

 in Porella. The lateral denticles of the primary orifice are well developed, but they may be equally 

 so in Lepralia. The avicularia, ooecia, and zooecial walls offer no distinctive characters. 



KEY TO SPECIES. 



1. Orifice rounded posteriorly, with a small, usually pointed, denticle or none; an avicularium imme- 



diately behind the orifice .porifera. 



Orifice more straight on the posterior margin, the denticle broader, without an avicularium close 

 behind the orifice 



2. Large, pointed avicularia in addition to others trispinosa. 



Large, pointed avicularia wanting trispinosa, var. niiida. 



Smittia porifera (Smitt). [PI. xxvi, fig. 64.] 



Smitt 1867, pp. 9 and 70 (Escharclla porifera). 



Verrill 1879)3, p. 192, and 18790, p. 30 (S. landsborovii). 



Hincks 1888, p. 225, and 1892, p. 156. 



Whiteaves 1901, p. 105 (S. landsboromiv&r. porifera). 



Zoarium encrusting stones, shells, and stems of various sorts, flat and smooth or more or less irreg- 

 ular. Zooecia large, ovate or more or less elongate, separated in the young colony by slightly raised 

 borders which are usually obliterated later by calcification of the front; surface at first smooth and 



