2 BULLETIN 71, UNITED STATES NATIONAL MUSEUM. 



Family 8. ROTALIID^. 



Test calcareous, perforate, composed usually of numerous chambers, 

 except in the subfamily Spirillininse, early chambers coiled, and 

 later chambers in typical genera spirally coiled so that the chambers 

 are all visible from the dorsal side and only those of the last formed 

 coil from the ventral side, convexity of the two sides varying greatly; 

 later development in specialized genera being columnar or even 

 arborescent. 



This family is one with a great variety of form and a wealth of 

 ornamentation especially in tropical species. Some of the genera, 

 such as Pulvinulina, make up a considerable percentage of Globigerina 

 ooze and as such are very numerous and widely distributed. Others, 

 such as Tinoporus often make up a considerable mass of the foram- 

 inif eral content of certain tropical shore sands, as in the Philippines 

 and elsewhere. 



There is a regular gradational development, although broken here 

 and there from the simple coiled, nonseptate SpiriUina to Rotalia, 

 where there is a tendency to complex form in supplemental skeleton 

 and internal tubular system reminding one of the Nummulitidse. 



Su.TDfam.ily 1. SPIRIILIjINrN^aE. 



Test free or attached, composed of a proloculum and a long coiled 

 tubular second chamber; variously ornamented; aperture at the end 

 of the tube; wall calcareous, perforate. 



This subfamily with the single genus SpiriUina is an excellent 

 parallelism in the RotaliidaB with the genus Ammodiscus in the 

 Lituolidse and Comuspira in the Miliolidse. There is a considerable 

 range of form and ornamentation, and most of the species are char- 

 acteristic of comparatively shallow water especially in the Tropics. 



Genus SPIRILLINA Ehrenberg, 1841. 



SpiriUina Ehrenberg (type, SpiriUina vivipara Ehrenberg), Abh. Akad. Wiss. 



Berlin, 1841, p. 422. — H. B. Brady, Rep. Voy. Challenger, Zoology, vol. 9, 



1884, p. 629. 

 Operculina Reuss (part), Denkschr. Akad. Wiss. Wien, vol. 1, 1849, p. 370 (not 



Operculina d'Orbigny, 1826). 

 Comuspira Schultze (part), Organ. Polythal., 1854, p. 41. 



Description. — Test typically free, occasionally attached, spiral, 

 composed of a subcircular or ovoid proloculum and a long undivided 

 tubular second chamber, coiled regularly in one plane; wall hyaline 

 and perforate; surface smooth or variously ornamented; aperture 

 formed by the open end of the tube. 



The genus SpiriUina is composed of few species, most of which are 

 minute. They are found Usually in comparatively shallow water 

 and seemingly most often on muddy bottoms. Some species seem 

 to prefer the mud of coral reefs. 



