266 SEA-SIDE STUDIES. 



a ciliated orifice ; on either side of the canal lie the 

 ova ; in the lower half, which is longitudinally divided 

 by a septum, the whole cavities are filled with granules 

 of various sizes, moving, by a scarcely perceptible 

 progress, round and round, like food in the stomach ; 

 and these granules prove to be the spermatozoa which 

 issue from the two orifices near the caudal expansion. 

 My species, which I have christened Sagitta Mariana, 

 is about the quarter of an inch in length, and differs 

 in several points from the species described and figured 

 by Mr Gosse in his Tenhy and Handbook, and by Mr 

 Busk in the Microscopical Journal.^ For instance, 

 it has no anterior fins ; and the posterior fins, which 

 arise near the oviducts, are continuous with the caudal 

 fin, into which they expand ; that is to say, it has 

 really but one fin on each side, with a caudal expan- 

 sion. Another peculiarity worthy of notice is, that, in 

 consequence of this union of the lateral and caudal 

 fins, the orifices through which issue the spermatozoa, 

 instead of opening directly in the integument of the 

 body, are openings in the fin itself ; as I have con- 

 vinced myself by repeated examination — a cu^cum- 

 stance which leads us to suspect that the "fin" is 

 only a membranous expansion of the integument, and 

 not properly a fin. Other details, not mentioned, and 

 therefore, I presume, not present in the specimens 

 previously described, but which were constant in those 

 found at Scilly, are the double band of light yellow 



* October 1855. In this paper the reader will find a summary of all 

 that was then known on the subject. 



