No. 1797. NEW TUBULIPOROID BRYOZOA—BASSLER. 501 



divergence. The differences, while often very shght, hold so well 

 that little diflBculty is encountered in recognizing species the world 

 over. For example, the genotype, Corynotrypa delicatula, and the 

 well-known C. inflata, so common in numerous Ordovician horizons 

 of America, have been recognized at several European localities. 

 C. ahrupta, C. dissimilis, C. harheri, and C. elongata are likewise 

 nearly cosmopolitan forms. 



With these points of terminology in mind, the genus may be defined 

 as follows: 



CORYNOTRYPA, ne^^v genus. 



Zoarium adnate, consisting of simple, subtubular zooecia arranged 

 in single-branched series; zooecia oval-pyriform to elongate clavate, 

 the proximal end constricted and united with the preceding zooecium 

 by a narrow, tubular stolon of variable length; the distal portion 

 more or less expanded and bearing on its frontal side the aperture 

 which is subterminal, circular, and inclosed by a more or less distinct, 

 slightly elevated peristome; walls finely porous. 



Genotype, Stomatopora delicatula James. Ordovician of America 

 and Europe. Range of genus, base of Ordovician to close of Meso- 

 zoic; probably also Cenozoic. 



The closest ally of Corynotrypa is undoubtedly the well-known and 

 even more widely distributed and longer-lived Stomatopora. The 

 two genera agree in having an incrusting zoarium composed of simple, 

 porous, tubular zooecia arranged uniserially. Corynotrypa differs 

 from Stomatopora most obviously in the constriction of the proximal 

 end of the zooecium, giving it the characteristic clavate to pyriform 

 shape which causes each to stand out as an individual. In Stomato- 

 pora the successive zooecia form a narrow branch with more or less 

 parallel sides in which the individuals are scarcely delimitable except 

 by their apertural openings. 



Among the species referred to Corynotrypa, the proximal constric- 

 tion is most evident in those assigned to the C. injiata and the C. deli- 

 catula groups discussed later, but becomes less marked in such forms 

 as C. canadensis and C. dissimilis. The last two represent a third 

 group in which the generic relationship to Stomatopora is much more 

 obvious. In addition to the shape of the zooecium, the aperture in 

 Corynotrypa likewise presents good generic characters. In typical 

 Stomatopora the aperture is exsert, usually slightly tilted forward, 

 and often almost equals the zoarial branch in diameter, Coryno- 

 trypa, in its two principal groups, has a small, neatly constricted 

 aperture, never exsert, with a width about one-third that of the 

 branch and surrounded by a low but distinctly marked peristome. 

 In the third or C. dissimilis group of Corynotrypa, the nearer relation 

 to Stomatopora is again expressed, in that the zooecial apertures are 

 occasionally exsert and of unusual width.- 



