of the vicinitij of Aberdeen. 333 



mature, drop off near their origin, or are torn away by the action 

 of the water. The frond never, I believe, produces fresli recep- 

 tacles, although it often remains attached to the rocks for some 

 time after the former have disappeared. 



jNIature specimens some time after being gathered readily give 

 out their hasisperms and acrosperms, the latter appearing in the 

 form of a slimy mucus. Plate VI. fig. 1. represents a not uncom- 

 mon form of the last ; in the same conceptacle, however, several 

 different varieties may be seen, owing no doubt to their not all 

 reaching matuiity at the same period. Fig. 3 represents the ripe 

 sporidia after expulsion from the asci which contained them. 



LiCHINEiE, 



Lichina confinis, Ag. — Of the two British species, this is the 

 only one which I have hitherto found on this coast, where it is 

 abundant on rocks a little above high -water mark. If the other 

 species does not actually grow here, this may be considered by 

 some an evidence in favour of the opinion that they are distinct 

 species, the one being considered by authors a mere variety of 

 the other. 



Laminarie^e. 



Alaria esculenta, Grev. — This plant is very abundant upon all 

 parts of the coast, and is most usually found near low -water mark. 

 Turner defines the fructification as consisting of " small pyriform 

 pellucid seeds, internally dotted, having on their largest extre- 

 mity a white transparent globule.^^ Dr. Greville, in his ' Algae,' 

 describes the fructification as being composed of " pyriform seeds, 

 vertically arranged in the incrassated leaflets ;" his figure, how- 

 ever, corresponds with Tm-ner's definition. In the latest work 

 on the subject to which I have access, Harvey's ' Manual,' Dr. 

 Greville's character of the fructification is adopted. After a careful 

 examination of numerous specimens in different stages, I am 

 constrained to call in question the accuracy of the above state- 

 ments. 



Fig. 3. tab. 4. of the ' Algae Britannicse' gives a good idea of 

 the structure of a perpendicular section under a low magnifier. 



With a higher power the true nature of the fructification be- 

 comes evident ; it consists of transparent clavate tubes [asci] in- 

 closing solitary simple spwridia. Turner's statement respecting 

 the terminal transparent globule must have originated from the 

 position of the inclosed sporidia in their asci, which is evident 

 from the accompanying figure. Fig. 3. Plate VI., the part of the 

 tube beyond the summit of the sporidium presenting an approach 

 to the figure of Greville when viewed with a low and ill-defining 

 lens. Fig. 4 represents a sporidium separately. The sm-face of 



