474 BULLETIN 106, UNITED STATES NATIONAL MUSKUM. 



Genus MUCRONELLA Hincks, 1880. 

 18SO. Mucronella HINCKS, British Marine Polyzoa, p. 360. 



The frontal is surrounded by areolae and covered by a pleurocyst, costulate or 

 granular. There is a lyrula and often some cardelles in the peristomice inferiorly. 



N "50 



P x50 Q 



FIG. 133. Genus MucronclJa Hincks, 1880. 



A-G. Mucronella peachi Johnston 1S47. A. Zooecia, X 50. B. Zooecia with ovicells, X 

 25. C, D. Old conditions, X 50, showing the growth of the pleurocyst over the surface E. Sep- 

 tulae, X 18. (A-E after Hincks, 1880.) F. Operculum, X 60. (After Levinsen, 1894.) 

 G. Lyrula, X 50. (After Waters, 1889.) 



H-U. Lyrulae, species of Mucronella. H-I. M. ventricosa Hassall, 1841, X 50, and X 85. 

 (After Waters, 1889.) J. M. labiata Boeck, 1861, X 85. (After Nordgaard, 1861.) K. M. 

 abyssicoJa Norman, 1868, X 85. L. M. laqueata Norman, 1868, X 85. M. M. peachi Johnston, 

 1847, X 85. (K-M after Nordgaard, 1905.) N. M. porosa Hincks, 1881, X 50. O. M. variolosn 

 Johnston, 1S3S, X 25. P. M. elleri MacGillivray, 1868, var. biamculata Waters, 1889, X 50. 

 Q. M. biincisa Waters, 1882, X 50. R. M. rostrata Hincks, 1880, X 50. S. M. levis MacGilli- 

 vray, 1882, X 25. T. M. spinosissima MacGillivray, 1879, X 25. U. M. diaphana MaoGillivray, 

 1879. X 50. (N-U after Waters, 1889.) 



Genotype. Mucronella (Lepralia) peachi Johnston. 1847. 



Range. Jacksonian-Eecent. 



The limits of this genus were rigorously established in 1904, by AVaters. It 

 differs from Smittina in the replacement of the avicularium by a mucro, that is to 

 say, by an organ which we know to be almost equivalent. 



