1885.] G. M. Giles— Ovi the Protliallus o/Padina pavonia. 71 



last three earthy-brown marked with madder-brown blotches. Anterior 

 three pairs of appendages subequal, of the usual amphipodal swimmeret 

 type. 4th and 5th pairs of appendages robust, biramous, the rami sub- 

 equal with short, stout, straight spines ; the fourth much larger than 

 the fifth. Gth pair of appendages short, stout, internal ramus almost 

 rudimentary, armed, like those of the 4th and 5th, with short, stout, 

 straight spines. Telson nodular with a few short spines. 



Explanation of Plate III. 



Fig. 1. Side view of Melita megacheles in natural colours, x 25. 



Fig. 2. Distal joints of 2nd gnathopod of the female specimen, x 20 about, 

 i. e., drawn as if belonging to a body on the same scale as fig. 1, to shew the compa- 

 rative size of these appendages in the two specimens. 



Fig. 3. Distal joints of antennular appendage, x 275, In the before-mentioned 

 dilated joint are some highly refractile bodies probably of the nature of otoliths. 



Fig. 4. Abdominal appendage of the 6th pair, x 60. 



VIII. — Natural History Notes from H. M's Indian Marine Survey Steamer 

 ' Investigator^'' Commander Alfred Carpenter, R. N., Gommandi^ig. 

 No. 3. On the Protliallus of Padina pavonia. — By G. M. Giles, 

 M. B., F. R. C. S., Surgeon-Naturalist, hidian Marine Survey. 



[Received April 21st ;— Eead June 6th, 1885.] 



(With Plates IV and V.) 



The reproductive process of the genus Padina is a subject which 

 has, I believe, been involved in some uncertainty. 



The most recent work which I possess that deals at all minutely 

 with the marine algas is the last edition of the Micrographic Dictionary. 



In this only one kind of " spore " is described alternating with tufts 

 of jointed hairs (paranemata) " which Agardh appears to have mistaken 

 for antheridia." This is, I believe, a correct surmise, more especially as 

 I have recently had the good fortune to meet with a body which, there 

 can be little doubt, is the prothalloid or sexual stage of the plant ; the 

 stage usually found being non-sexual, like that of fully formed ferns. 



To the description of the adult plant, as given in the above-quoted 

 work, there is little or nothing to add ; but the spores dropped from its 

 indusia give rise not to a similar form but to an alternate stage possess- 

 ing both kinds of sexual organs. 



Padina pavonia is a weed very common on the coast of British 

 Burmah, growing on rocky spots, more especially in situations where there 

 is a good deal of sand and mud in the interstices of the rocks. 



