25 
Dr. Reid on the Development of the Medusae. 
semicircular plate^ armed at its edge with numerous slender setae. 
The second is shorter and has several long plumose hairs spring- 
ing from its inferior edge^ and three or four not plumose from 
the upper surface. The terminal joint gives off at its apex four 
stout setae^ and numerous others more slender from its upper 
edge. The first pair of jaws (fig. 6) consists each of a semi- 
circular plate furnished on its convex margin with a great num- 
ber of long beautifully plumose filaments, and has attached to 
one extremity two other plates, each provided with numerous 
very slender setae on their edges. The second pair of jaws (fig. 7) 
consists each of a semicircular plate furnished on its inner margin 
with numerous long slender setae disposed like the teeth of a 
comb. At one end it gives off a stout branch like a finger, 
w'hich is terminated by seven or eight long curved spines, and 
at the other sends off seven or eight long stout plumose setae. 
The organs represented at fig. 8 are perhaps the mandibles, 
but as I did not observe their exact situation in the animal, I 
cannot with certainty refer them to those organs. The part repre- 
sented (fig. 9) is unique, but I do not know its nature or use. 
EXPLANATION OF PLATES VI. B. and VII. 
Plate VI. B. Fig. 1. C. MacJndrei, highly magnified. 
Fig. 2. The outer shell removed to show the animal. 
Fig. 8. Anterior antenna. 
Fig. 4. Natatory foot. 
Fig. 5. Second pair of antennae. 
Fig. 6. Oviferous foot. 
Fig. 7. Tail. 
Plate VII. Fig. 1. C. Adamsi, slightly magnified. 
Fig. 2. Anterior antenna. 
Fig. 3. Natatory foot. 
Fig. 4. Oviferous foot : a. portion highly magnified ; h. one of 
the spines highly magnified. 
Fig. 5. Second pair of antennae. 
Fig. 6. First pair of jaws. 
Fig. 7. Second pair of jaws. 
Fig. 8. Mandibles ? 
Fig. 9. ? 
III. — Obsey'vations on the Development o/ Medusse. By John 
Reid, M.D., Fellow of the Royal College of Physicians of 
Edinburgh, and Chandos Professor of Anatomy and Medicine 
in the University of St. Andrews* *. 
[With two Plates.] 
The following observations were made upon three colonies of the 
larvse of a Medusa. One of these was procured on the 15th of 
* These observations were laid before the Literary and Philosophical 
Society of St. Andrews at the Meetings of the 4th of May 1846 and the .5th 
of April 1 847, and abstracts of them were printed in the ‘ Transactions ’ of the 
Society, and reprinted in Nos. 118 and 131 of the first series of this Journal. 
