4 Beecher —Observations on the Genus Roniingeria. 



In 



a careful 

 1 



4t 



count of 



12 11 10 9 8 7 



Figure 1. — Frequency polygon 

 ot Romingeria umbelUfera; show- 

 ing the number of buds in a hun- 

 dred umbels ; the abscissa shows 

 the variation in the number of 

 buds per umbel (seven to twelve), 

 and the ordinate the number of 

 individuals representing each. 41 

 per cent of the umbels have 

 twelve buds, 28 per cent eleven, 

 16 per cent ten, 6 percentnine, 

 5 per cent eight, and 4 per cent 

 seven. 



one hundred discrete whorls, the 

 writer has found that 41 per cent 

 contain twelve buds, 28 per cent 

 contain eleven, 16 per cent ten, 6 

 per cent nine, 5 per cent eight, and 

 4 per cent seven buds. In no 

 instance has any number greater 

 than twelve or less than seven been 

 observed in separate nmbels. The 

 very unusual condition represented 

 in the specimen, figures 8, 9, Plate 

 I, shows two verticels crowded 

 together so as to unite, and eleven 

 coi-allites are suppressed in conse- 

 quence. Of the fifteen remaining 

 corallites, two {a, Z>,) are the parents, 

 while six pertain to one umbel and 

 seven to the other. 



The frequency polygon is shown 

 in text, figure 1. This indicates, that 

 what Billings meant by "sometimes 

 ten or twelve " buds really means 

 that 85 per cent of all the umbels 

 have from ten to twelve buds 

 springing from the parent coral- 

 lite, and that twelve is the most 

 common and therefore the charac- 

 teristic number. There is a rapid 

 falling off in the numbers below 

 ten, and specimens with less than 

 that must be considered as abnor- 



mal or pathologic. 



The length of the internodes or the distance between the 

 whorls measured along the corallites varies from 8 to 23°"". 

 Since the budding period is simultaneous for the whole corallum, 

 and takes place on the same horizontal plane, it is evident that 

 the internodes measured along one of the older parent corallites 

 are shorter than along one of its daughter corallites, which rise 

 obliquely from their origin to the next budding zone 



The corallites measure from 2 to 2*25 

 out most of their length. Just before starting to bud the tube 

 enlarges to a diameter of 2*50 to 3™"", and within the whorl of 

 buds the parent corallite abruptly contracts to about 1-6'"'" in 

 diameter. The buds all spring from the beveled periphery of 

 the parent corallite, with which they communicate by means 

 of a large initial pore, figures 2, 3, Plate I. Both buds and 



^ in diameter through- 



