CORYNOTRYPA, A NEW GENUS OF TUBULIPOROID 



BRYOZOA. 



By Ray S. Bassler, 



Curator of Invertebrate Paleontology, TJ. S. National Museum. 



INTRODUCTION. 



The present paper discusses all the known species of a supposed 

 new genus of simple tubuliporoid Bryozoa, and may be said, there- 

 fore, to be monographic in its scope. However, the prime object of 

 the article is the determination of the specific variation in a group 

 of tubular organisms, which, on account of their minute size and 

 extreme simplicity as well as alleged great variability of structure, 

 have presented difficulties of classification. 



In almost every class of natural history in which tubular organisms 

 occur, the classification of these simpler types has proved more diffi- 

 cult than that of their more complicated allies. This is particularly 

 true in the case of the Bryozoa where the simplest of such tubular 

 forms are grouped imder the family Tubuliporidse, in the order 

 Cyclostomata. A wide difference of opinion has obtained even 

 among the best students as to the classificatory value of the few and 

 supposedly quite variable characters exhibited by these types, and 

 their literature therefore presents varying degrees of exactness. 

 For example. Waters, an excellent but very conservative student, 

 considered the early Ordovician form Mitoclema cindosum to be the 

 same as the late Mesozoic Sjnropora verticillata, while Haime included 

 in one species specimens which d'Orbigny had divided among five 

 genera. In spite of such extreme views there is a growing tendency 

 among present-day students to recognize as genera in these simple 

 bryozoans those groups, distinguished mainly by method of growth, 

 around which the various species may be assembled. Gregory ** has 

 given an interesting discussion on the value of generic divisions in 

 the Cyclostomata, arriving at the conclusion that the terms Stoma- 

 topora, Prohosdna, and like names applied to the simple bryozoans, 

 might be accepted, not as generic names in the sense in which this 

 term is used in the higher groups of animals, but as designations for 

 convenient groups not altogether artificial. He says: "They could 



a Cat. Fobs. Bryozoa British Museum, The Jurassic Bryozoa, 1896, pp. 14-22. 



Proceedings U. S. National Museum, Vol. 39— No. 1797. 

 Proc.N.M.voU39— 10 34 497 



