116 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.61. 



Genus CRISINA D'Orbigny, 1852. 



1852. Crisina d'Orbigny, Paleontologie frangaise, Terrain Cretace, vol. 5, 



p. 912. 

 1887. Crisidmonea Maksson, Bryozoen der weissen Schreibkreide der Insel 

 Riigen, Paleontologische Abhandlungen, vol. 4, p. 30. 



The ovicell is a globular sac, very salient, unsymmetrical, inclosing 

 the opposite lines of each side of the median crest on almost all of the 

 zoarial width. The inclosed peristomes are more salient and larger. 

 The tubes are short, club shaped, with triparietal gemmation ; their 

 calcareous walls are very thick at their extremity. The dorsal is 

 very thick, of lamellar structure, and perforated by scattered 

 vacuoles. 



Genotype. — Crisina noivnaniaiia D'Orbigny, 1852. 



Range. — Cenomanian-Campanian. 



This genus is very close to Pohjascosoecia and differs in its ovicell 

 covering all the zooecial width, in the absence of frontal mesopores, 

 and in its short club-shaped tubes with dilated walls. 



The structure of the genus Grisldmonea Marsson, 1887, is identical, 

 but its ovicell is not known. 



The known species are: Crisina 7ior7naniana D'Orbigny, 1850; C. 

 trmngulans D'Orbigny, 1851; Crisina subgradaia D'Orbigny, 1850; 

 Crisidmonea macropora Marsson, 1887; Idmonea prima Pocta, 1892; 

 and /. ci^etacea Milne-Edwards, 1838. 



The genus Crisina of D'Orbigny is also one which has been poorly 

 interpreted by the authors who have succeeded him and which it is 

 necessary to reestablish within the exact limits fixed by the French 

 paleontologist. His definition is as follows: "Colonic fixe par sa 

 base, d'ou partent des rameaux libres, anguleux, divises par des 

 dichotomisations sur le mCme plan, representant un ensemble den- 

 droide. Chaque branche est mince en dessus, de chaque cote, de 

 lignees ti ansversales de cellules, occupant chacune un des cotes, et 

 alternant entre elles au milieu. Le dessous off re, par lignes longi- 

 tudinales, des pores opposes plus ou moins larges, non saillants et 

 souvent dans des fossettes longitudinales. L'accroissement a lieu 

 seulement a Fextremite des rameaux par des germes de cellules; 

 quelquefois des vosicules ovariennes sur le cote des rameaux sous 

 forme de boursouflures." 



D'Orbigny did not wish to classify in this genus all the Idmoneas 

 provided with pores of whatever nature on the reverse. The three 

 species which he has described are provided with widely spaced pores 

 (vacuoles) placed at the base of longitudinal fossettes (sulci). The 

 sections which we have made of Crisina friangularis and normaniana 

 confirm entirely this interpretation of his text. 



D'Orbigny has classified in the same genus three species of Reuss 

 not provided with sulci and only from an examinataion of the figures. 



