262 MYRIOZOID.E. 



and is situated on the top of a mamillary swelling imme- 

 diately below the inferior margin of the mouth. In other 

 states, however, some of the mamillae, especially towards 

 the edge of the colony, are found of much larger size, 

 bearing an elongated avicularium of somewhat oval shape. 

 In others the increase in size has been carried much 

 further, accompanied by a striking modification in the 

 form of the avicularium, which is now distinctly spatulate. 

 A specimen of S. auriculata, in which a considerable num- 

 ber of the cells have passed into this condition, presents 

 a very remarkable appearance the avicularia, with their 

 large rounded extremities, projecting beyond the ma- 

 millary eminences on which they are mounted. In the 

 interior of the colony cells may be found which bear the 

 usual character. 



In the var. marked a (ochracea) there is considerable 

 divergence from the normal type. In most of the cells 

 the avicularia, instead of being elevated and placed imme- 

 diately below the mouth, are situated at some distance 

 from it, on the front surface, and are completely im- 

 mersed. They are small, and oval or subcircular in shape. 

 Many of the cells, however, bear avicularia that may 

 truly be called gigantic. They extend from a little below 

 the orifice to the bottom of the cell, and are so ample as 

 almost to cover the front surface. They have not the 

 truly spatulate figure which distinguishes the large avicu- 

 laria just mentioned, and are best described as linear- 

 oblong. The sides are not hollowed out, nor is the extre- 

 mity enlarged. 



So striking are the peculiarities of this form that I 

 at first regarded it as a distinct species, and described it 

 under the name of Lepralia ochracea. I am now con- 

 vinced, however, that these variations in the avicularium 

 are not characters of specific value. On a specimen of 



