24 



LESUEURIA. 



find corresj)onding to the complicated windings of the longitudinal 

 ambulacra are a few short, straight projections of the ambulacral tubes, 

 runnmg like spurs into the thickness of the spherosome. 



The outline of our Lesueuria (Fig. 25) is entirely different from that 

 of the Mediterranean ; the latter is quite ellipsoidal, while the North 

 American species shows a strong tendency to bulging out near the 

 actinostome, and to imitate in its outline that of Bolina, mutilated 

 sj)ecimens of wliich, when seen swimming in the water, can easily be 

 mistaken for this species. It is only on noticing the position of the 

 mouth, the great length of the auricles, that the mistake becomes 

 apparent. Lesueuria is as transparent as Bolina, and even more slug- 

 gish ; it grows to a large size, four inches in polar diameter, and is 

 exceedingly abundant during September, large numbers being visible 

 on almost any clear, hot day. Its phosphorescence is a very peculiar 

 bluish Hght, of an exceedingly pale steel color, but very intense. 



AVhat is j)eculiar to our species is the almost rectangular outline 

 which it has when seen from the broad side (Fig. 25). The shortness 



Fig. 25. 



Fig. 26. 



of the funnel ; the extreme tenuity of the chymiferous tubes ; the deep 

 depression, or rather cut, in which the eye-speck is situated, for the 

 abactinal part of the gelatinous spheromeres joins so closely above this 

 that the eye-speck literally seems imbedded in the solidity of the 



Fig. 25. Lesueuria seen from the broad side, natural size. 

 Fig. 26. Fig. 25 seen from tlie narrow side. 



