300 



BULLETIN 11, UNITED STATES NATIONAL MUSEUM. 



The most marked character seen in vertical sections or in longi- 

 tudinal fractures is the great crinkling of the zooecial walls in the 

 immature region and the almost entire absence of diaphragms in 

 this and the mature regions. In the latter the zooecial walls thicken 

 greatly, the crenulation is less marked or disappears entirely, and 

 acanthopores are developed. Mesopores, which occur only in the 

 mature region, are distinguished with difficulty on account of their 

 similarity to the ordinary zooecia. The thick walls, small acantho- 



FlG. 184.— ANAPHEAGMA MIRABILE COGNATA. a, VIEW OF FKAGMENT, NATURAL SIZE; 6, TANGENTIAL 

 SECTION, X20, WITH WALL STRUCTURE PLAINLY MARKED; C AND d, VERTICAL SECTION, X8, AND A POR- 

 TION, X20. WASSALEM BEDS (D3), UXNORM, ESTHONLi. 



pores, and the black line separating adjoining zocBcia, are well shown 

 in tangential sections. 



The present species differs so much from associated ramose bryo- 

 zoans in the practical absence of diaphragms and the strong, crenu- 

 lated walls, that comparisons are unnecessary. Critically compared 

 with AnapJiragma mirabile, however, it is found to agree in growth, 

 thickness of zooecial walls, and in most of the internal characters, 

 differing only in that the walls are more crenulated and that the 

 zooecia are a trifle smaller. These differences are possibly of specific 



