FORAMINIFERA OF THE NORTH PACIFIC OCEAN. 7 



instead of the usual nonseptate condition. In all, 12 partitions 

 were made out. After the proloculum (fig. 5) there are three com- 

 plete coils of nonseptate tube, as in ordinary specimens. Then the 

 tube is cut off by a ''partition." Following this are three and three- 

 quarters coils of nonseptate tube and then another "partition." 

 About a quarter coil beyond is a third "partition," then in each 

 succeeding coil a "partition" is found when a coil has been nearly 

 completed. Again, there is a quarter coil followed by a "partition." 

 From this point there are six "partitions" in the following five coils, 

 without any definite arrangement. A figure shows the arrangement 

 in the earlier chambers (fig. 5). 



Fig. 5.— Cornusptea foliacea (Philippi). X 116. Early coils of microspheric specimen showing 



THE "PARTITIONS" I>UVELOPED AT IRREGULAR INTERVALS IN THE TUBULAR CHAMBER. VIEWED BY 

 TRANSMITTED LIGHT. 



Both microspheric and megalosplieric specimens occur in various 

 species of the genus. A megalosplieric (fig. 3) and microspheric 

 specimen (fig. 2) of Cornuspira involvens are here shown in the same 

 magnification. The number of coils in general is in inverse ratio 

 to the size of the proloculum in the two, but, as is usually the 

 rule in the foraminifera, the microspheric form attains the greater 

 size. 



Development of Optlialmidium. — The developmental stages of 

 pthalmuHum inconstans H. B. Brady may be taken as showing the 

 general characters of the genus. In this species (fig. 6) there is the 



