146 Linnean Society. [June 17, 



Cape of Good Hope. These were of two kinds, one occurring as 

 upright cylindrical bodies, and the other in the form of spreading 

 aloe-like groups of fleshy leaves ; both being found in the sandstone 

 of the district near Wynberg. 



Read a Letter from Thomas Forster, Esq., M.B„ F.L.S., dated 

 from Bruges, May 21st, 1851, and addressed to the Secretary, con- 

 taining some observations " On the present season in relation to 

 the Migration of Birds and other Natural Phaenomena." 



Dr. Forster commences his letter by referring to a passage in 

 White's ' Natural History of Selborne,' where it is remarked that 

 the Swallow-tribe, and particularly the Martins, must suffer great 

 devastation in the course of their winter migrations, inasmuch as, in 

 certain seasons " the numbers of single birds which return in the 

 spring bear no manner of proportion to those who retire in autumn." 

 Dr. Forster's Journal, now of forty years' standing, shows that this 

 disproportion is greatest in late springs, particularly when accom- 

 panied with much wet and windy weather. The present season has 

 been especially remarkable. After a winter the mildest ever re- 

 membered in Belgium, the spring was cold and showery, and nearly 

 all the periodical phsenomena were later than usual ; while many 

 tribes of plants suffered severely from some obscure atmospherical 

 influence, apparently referable to the same class of causes which 

 produce epidemics in the human subject and epizootics among 

 animals. The Hyacinthus plumosus died off in most gardens, and 

 also the Muscari racemosus. As soon as the flowers showed them- 

 selves the stock began to wither and in a few days died away, whole 

 beds going off in the same way. Great numbers of Tulips perished 

 in the ground ; the leafing of trees was very late ; and the Mulberry 

 had not at the date of the letter shown any signs of budding. ITie 

 Swallow {Hirundo rustica) arrived on the 1 8th of April, and had 

 become pretty numerous. The Swift {Hirundo Apus) came on the 

 7th of May, in less numbers than usual. Dr. Forster had not yet (on 

 the 21st of May) seen the Sand-Martin (^Hirundo riparia), which is 

 usually found in April ; and even of the Martin (^Hirundo urbica^, 

 usually plentiful at Bruges in the first week of May, the most care- 

 ful search had not enabled him to detect a single bird. The Night- 

 ingale and Black-cap came to their time, but the Grey Wag-tail 

 was not seen until the day of the date of the letter. The remarkable 

 scarcity of flying insects, the usual food of the swallows, caused them 

 to seek for other species, and a natui'alist of the neighbourhood had 

 assured Dr. Forster that he saw them hunting for their prey on 



