176 Miscellaneous. 



The Caudal Styles of Insects Sense-organs, i. e. Abdominal Antennce. 

 By Dr. A. S. Packard, Jun. 



Dr. Anton Dohrn has published a note, in the ' Journal of the 

 Entomological Society of Stettin ' (1869), to the effect that the 

 abdominal appendages of the female of the mole- cricket (Gri/llo~ 

 taljxi) are true sensory organs (Tastorgane). 



In the ' Proceedings of the Boston Society of Natural History,' 

 May, 1866, the writer states that " -while, as we have shown above, 

 the genital armour of insects is not homologous with the limbs, 

 there are, however, true jointed appendages attached to the ninth 

 or tenth abdominal ring, or both, which are often antenniform, and 

 serve as sensorio-genital organs in most [many] Neuroptera and 

 Orthoptera " (p. 290). 



In the same 'Proceedings' for February 26, 1868, he thus writes : 

 " Regarding the insect as consisting of two (fore and hind) halves, 

 the two ends being, with this view, repetitions of each other, these 

 anal stylets may be considered as abdominal antennae, so that the 

 antennae look one way, and their homologues, the many-jointed 

 antenniform anal stylets, the opposite " (p. 398). 



The subject is ako referred to in the ' Guide to the Study of 

 Insects,' p. 17 ; and the remarkable antenniform abdominal appen- 

 dages of Mantis tessellata are figured in illustration. 



I have been able to detect sense-organs (probably endowed with 

 the sense of smell) in the short, stout, jointed anal stj-lets of the 

 cockroach (Periplaneta americana), beautifully mounted by Mr. E. 

 Bicknell, having recently, after reading Dr. Dohrn's note, observed 

 the sense-organs and counted about ninety* minute sacs on each 

 stylet, which are probably smelling or auditory organs, such as 

 are described by Hicks (see ' Guide,' p. 26). They are much larger 

 and much more numerous than similar sacs in the antenna; of the 

 same insect, and are situated in single rows on the upperside of 

 each joint of the stylets. During the breeding-season a peculiar 

 odour is perhaps emitted by the female, as in vertebrate animals ; 

 and it is probable that these caudal appendages are endowed with 

 the sense of smell rather than of hearing, that the male may smell 

 its way to its partner. This is an argument that the broadly pecti- 

 nated antennge of many moths are endowed rather with the sense 

 of smelhng than of hearing, to enable the males to smell out the 

 females. I have observed the same organs in the lamellao of the 

 antenna) of the carrion-beetles, which undoubtedly depend more on 

 the sense of smell than that of touch or hearing to find stinking 

 carcasses in which to place their eggs. — American Naturalist, vol. iv. 

 Dec. 1870. 



* Mr. Bicknell has counted more carefully than I did the exact number 

 of these pits, and uiiide out ninety-five on one stylet and one hundred 

 and two on the other, adding, " there were none on the underside of their 

 appendages that 1 could see." 



