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BULLETIN 104, UNITED STATES NATIONAL MUSEUM 



there is any real specific difference existing between them; but for 

 purposes of convenience it is desirable to separate the small truly 

 globular and solid specimens (which are also characterized by smaller 

 vesicular chambers) under the name of G. globulus, and to assign to 

 G. vesicularis the larger and coarser forms, whether their shape be 

 compressed, convex, or biconvex, or even sub-spherical, as is frequently 

 the case. These sub-spherical specimens really constitute the greatest 

 difficulty, for they are practically indistinguishable from G. globulus 

 except by their larger size and coarser areolation; but when regarded 

 from the point of view of an extensive series of specimens, such as 

 can be obtained at many stations in the area of the Clare Island 

 Survey, the difficulty of discrimination is diminished by the fact 

 that globular specimens of intermediate size are seldom or never 

 found. G. vesicularis appears to begin its growth as a convex boss 

 with a flat base, becoming first lenticular, and subsequently, in the 

 largest specimens, almost truly spherical, whereas G. globulus begins 

 with a minute spherical test, and increases in size by the addition of 

 concentric layers. We figure an interesting variety of G. vesicularis, 

 specimens of which have been found at many stations, in which the 

 sub-globular test is a mere hollow shell. This variety presumably 

 has its origin as an encrusting layer over some rounded and perishable 

 body such as the terminal joint of a coralline. It is difficult to 

 conceive in what other circumstances this peculiar form can have 

 been assumed. The interior chambers of the sphere are always in a 

 good state of preservation, showing no signs of erosion. Although 

 we have not observed British specimens of G. vesicularis in the sessile 

 condition, we have no doubt that the animal frequently assumes this 

 habit, as many individuals are to be found in which the flattened base 

 corresponds in moulding to the shape of molluscan fragments such 

 as are common in the material." Their figures are reproduced here. 



GYPSINA VESICULARIS (Parker and Jones), var. DISCA Goes 



Gypsina vesicularis (Parker and Jones), var. discus Goes, Bull. Mus. Comp. 

 ZooL, vol. 29, 1896, p. 74, pi. 7, figs. 4-6. 



Under this name Goes has figured and described forms from the 

 Caribbean which have a biconvex form with rounded periphery. 



