82 Mr. J. Miers on the Tribe Colletiese, 



I will now advert to the other anomalous fact, in regard to 

 the raphe, above alluded to. Botanists have always attributed 

 to the seed of Rhamnus a chartaceous testa, with a raphe as a 

 simple cord, that runs up its external face, or along one side, in 

 a deep groove formed by a conduplicature of the whole seed, 

 and then terminates in the apical chalaza ; but one important 

 circumstance connected with this structure has been altogether 

 overlooked. I have found that this cord has a peripherical 

 range similar to that in Colletia, with this difference, that in- 

 stead of running laterally round it in the line of the margins of 

 the cotyledons, it is directed along the middle of one cotyledon, 

 in a deep groove upon the dorsal side, then crosses over the 

 chalaza without any apparent interruption in its course, and 

 returns down the ventral side in a direction close to the median 

 line of the other cotyledon, till it again reaches the hilum. 



As this structure is at variance with recorded descriptions, it 

 is necessary to state the circumstances more in detail. My first 

 observations were made upon the dried seeds of Rhamnus cathar- 

 ticus : this seed is smooth, of a hepatic brown colour, and of a 

 flattish oval shape, somewhat tapering to the base, where it is 

 callous and more polished ; it is a little angular upon the ven- 

 tral face, and rounded upon the dorsal side, along which is seen 

 a line running from the apex to the base : on pressing it, this 

 line is found to be the margin of a deep chink, which extends 

 all the way down to the axis of the seed. If we carefully remove 

 the outer coating, we find it rather thin, very brittle, and crus- 

 taceous, thus exposing a second tunic, which is very fine in 

 texture, membranaceous, and polished, and upon its ventral 

 side, opposite to the dorsal chink, is seen a distinct line running 

 from the base to the apex, where it passes over a large areolar 

 disk, arid runs into the summit of the chink in continuity with 

 the main cord of the raphe. If we take another seed, and cut 

 it in two transversely, we see the outer brittle tunic just men- 

 tioned becoming somewhat thicker as it approaches the dorsal 

 chink, where it is continued by in duplication, in the form of two 

 rather thick crustaceous plates that line the sides of the chink, 

 the internal edges of these plates being quite disconnected with 

 each other : it is evident, therefore, that this outer covering is 

 not an entire tunic ; for if it were unfolded, it would be found to 

 be merely a thin plate with thick margins, which are introflected 

 in the manner described, In the bottom of the chink, which 

 widens towards the axis, is seen a thin membranaceous dia- 

 phragm, that forms one side of a square hollow cavity which 

 runs through the axis from the apex to the base, and which 

 diaphragm is found to be a portion of the second thin polished 

 membranaceous tunic before mentioned, that lies beneath the 



