EUCHEILOTA DUODECIMALS. 75 



bell, with tentacular cirri well developed ; two marginal capsules be- 

 tween each tentacle, and rudiments of four additional tentacles half- 

 way between the capsules. (Fig. lOo.) These tentacles have at first no 

 lateral cirri ; it is only when they have assumed the shape of the lower 

 basal part of a full-grown tentacle that the cirri appear like two round 

 knobs, which are rapidly developed into lateral cirri before the lash of 

 the tentacle has been formed. The form of the young Medusa, with 

 only four tentacles, is globular, but it soon becomes flattened as it ad- 

 vances in growth. The digestive cavity is a simple long Fig.ios. 

 tube, hanging stiffly in the interior of the bell, which has 

 a very small circular opening ; the chymiferous tubes are 

 wide ; the basal swelling of the tentacle is large and coni- 

 cal, narrowing very rapidly into the thread of the tentacle 

 itself, which is exceedingly slender, with thin walls, and 

 lasso cells scattered irregularly over its surface. The 

 marginal capsules contain only one granule, while Mc- 

 Crady's species contains three or four. This may prove to be the 

 specific difference between these young specimens and the Charleston 

 species, as I have not, even in those specimens which had already eight 

 tentacles, found more than one granule, except in a single case two, in 

 one of the capsules. 



Charleston, S. C. (McCrady) ; Buzzard's Bay, Naushon (A. Agassiz). 



Eucheilota duodecimalis A. AGASS. 



Euclieilota duodecimalis A. AGASS. ; in Agassiz's Cont. Nat. Hist. U. S., IV. p. 353. 1862. 



This species differs from the above in having twelve marginal cap- 

 sules, one on each side of the four large tentacles (c, Fig. 107), and one 

 in the middle of the circular tube (Fig. 106) ; there are four long ten- 

 tacles, with lateral cirri (t f , Fig. 107) Fig.ioe. 

 and long slender lashes, which are 

 covered with lasso cells ; the chymif- 

 erous tubes are wide, and from their 

 point of junction with the circular tube 

 arise ribbon-shaped genital organs (o, 

 Fig. 107), which do not extend more 

 than one third of the length of the 

 chymiferous tube (Fig. 106) ; the 

 disk is of very uniform thickness, the 

 inner and outer surface of the bell being almost concentric to the very 



Fig. 105. More magnified view of a quarter of the disk, to show the position of the capsules 

 and tentacular cirri. 2, the second set of tentacles in Figs. 104, 105. 

 Fig. 106. Eucheilota duodecimalis A. Agass. ; greatly magnified. 



