556 APPENDIX C. 



Megnin (' Journ. Anat. et Physiol.,' 1877 and 1879) and others. 

 Robertson alludes to the close resemblance of Montagu's Cellu- 

 laria bassani to this, and anyone who compares the figures of 

 the two must be struck by their similarity. Megnin found 

 Hypodectes columbce to be a hypopial stage of an Analgesid 

 or Bird mite Pterolichus (now Falculifer) rostratus, Buchholz. 

 Now, the only Analgesid that appears to have been recorded 

 from the Gannet is Freyana (subgen. Michaelia) caput-medusce 

 Trouessart {see new edition of Naumann's ' Naturgeschichte 

 der Vogel Mitteleuropas,' and Canestrini's ' Sarcoptidse ' in 

 ' Das Tierreich '). It seems, therefore, highly probable that 



Montagu's Cellularia bassani — a name which, by the way, one 

 looks for in vain in Canestrini's work — is a hypopial stage of 

 this mite." 



If this be so, it will in future stand 3iS Freyanabassani (Mont.), 

 I presume. 



Mr. Evans suggests that the best time to look for the hypopus 

 would be the Gannet's moulting-season, as he thinks this sub- 

 cutaneous stage of the mite may perhaps be a provision against 

 its being thrown off with the feathers. 



An Acarid has also been found in the subcutaneous air-cells 

 of the Black-tailed Gannet, Sula capensis {see Sclater and Stark, 

 " Birds of South Africa," Vol. IV., p. 775), and it is almost 

 certain that the Australian Gannet, S. serrator, has one also, 

 but whether they are identical with the Acarids which infest 

 S. bassana remains to be proved by some specialist. 



Mr. Evans further informs me that Canestrini and Kramer 

 in their " Sarcoptidae " mention two other Bird mites as 

 found on the Tropical Gannets, namely Pteronyssus circiniger 

 Trt., found on Sula fiber, the Brown Booby, from the 

 Philippines ; and Nealges poppei, Trt., on Sula piscator, the 

 Red-footed Booby, from New Zealand. 



