Literary Notices. xvii 



plexus choroideus, exceptional. The exact figures upon which the 

 conclusions as to variability are based are given in the subjoined 

 table. 



Total number of embryos examined 47 



♦' " " cases of certain absence 25 



•' '* " " " presence 20 



" " " doubtful cases (added to the positive cases in the rest of 



the table) 2 



Total number of accessory eyes observed (including the doubtful cases and 



two cases of double eyes and two cases of triple eyes) 28 



Interparieto-epiphysial eyes 16 



Epiphysial eyes 7 



Interparietal eyes 4 



Choroid eye i 



Any criticisms of the morphological value of these eyes should be 

 reserved until the author's final paper appears. But whatever this 

 significance may be, this extreme variability certainly has its signifi- 

 cance. This is another and a very interesting case illustrating the ex- 

 treme variability so often found in organs which are either degenerate 

 or which for any other reason may be undergoing retardation or accel- 

 eration in the phylogenetic development. 



C. J. H. 



The Anteuiiary Auditory Organ of Insects ^ 



The first account of the auditory organ of the mosquito seems to 

 be that of Johnston, who in 1855 described a pair of pyriform cap- 

 sules between the eyes from which spring the antennse. " The space 

 between the inner and outer walls of the capsule, which we may con- 

 fidently term the auditory capsule, is filled with a fluid of moderate 

 consistency, opalescent, and containing mmute spherical corpuscles, 

 and which probably bears the same relation to the nerve as does the 

 lymph in the scalse of the cochlea of higher animals. The nerve 

 itself of the antenna proceeds from the first or cerebral ganglion, ad- 

 vances toward the pedicle of the capsule in company with the large 

 trachea which sends its ramifications throughout the entire apparatus, 

 and, penetrtaing the pedicle, its filaments divide into two portions." 

 Johnston sought to show that the long hairs of the antennae are grad- 

 uated to respond to sonant vibrations of different lengths. Mayer 

 studied the organ in living insects and '.observed the vibration of cer- 



'Child, C. M. Ein bisher wenig beachtetes antennales Sinnesorgan der 

 Insecten. Zcitsch. Wiss. Zool.y LVIII, 3, 



