49 



ly continuous with that in the peduncle. In Aurelia, Cyanea, and 

 other Aealephs, this substance aj^peai's like an amorphous gelatiniform 

 or semicartilaginous mass, with a few irregular cells scattered here 

 and there ; but in Lucernaria it has a highly organic structure. Ex- 

 tremely elongate, columnar, cell-like bodies extend in close proximity 

 from the outer to the inner wall, so that, in a section of the thickness 

 of the disc, it appears to be transversely striated. In the peduncle, 

 as a transverse section reveals, these columnar cells are arranged 

 about the axis in peculiar, regular groups ; some columns pass from 

 one channel to the next on either side ; some diagonally across the 

 axis from one channel to an opposite one, and others extend obliquely 

 from the channel to the muscular cords which alternate with them. 

 This arrangement reminds one of the methodical disposition of the 

 great cells in the body of Pleurobrachia, as I have described them in 

 Prof. Agassiz's third volume of his " Contributions to the Natural 

 History of the United States." In the oral or lower side of the disc 

 of Aurelia the gelatiniform substance has the same structure as in the 

 aboral side, whilst in Lucernaria, although it has all the regularity in 

 the disposition of its components that obtains in the aboral side, yet 

 it possesses a totally difl'erent nature, as I will describe hereafter in 

 connection with the muscular system. 



From the middle of the base of each of the four flat sides of the 

 quadrate proboscis a light streak, which has the deceptive appearance 

 of a radiating canal, passes in a direct line neai'ly to the border of the 

 disc ; this is the line along which the oral and aboral floors of the 

 disc unite, and form a solid partition, by which the digestive cavity is 

 divided into four broad chambers, which communicate with one an- 

 other at the inner or proximal ends, about the base of the proboscis, 

 and also at the outer or distal ends through the narrow passage be- 

 tween the terminus of the partition and the edge of the disc. In the 

 peduncle there are four equi-distant broad tubes, which merge into 

 one cavity at its base, and correspond in position to the four cham- 

 bers of the digestive cavity. The grouped tentacles which occupy 

 the eight corners of the disc are hollow, as, likewise, are the auricles, 

 and communicate openly and directly with the digestive cavity. This 

 is all that constitutes the chymiferous circulatory system of Lucerna- 

 ria. In Aurelia we have radiating canals at the points corresponding 

 to the partitions of Lucernaria, as well as in the intermediate sec- 

 tions. 



In Aurelia, the genitalia are four single circular organs, one of 

 each being placed opposite the flat side of the proboscis ; whereas in 

 Lucernaria each genital is a double organ, the halves of which have 

 a peculiar shape, and are situated respectively one on each side of 



PROCEEDINGS B. S. N. H.— VOL. IX. 4 JULY, 1862. 



