MR. TUFFEN WEST ON THE FOOT OF THE FLY. 403 



their tibiae. But with the Strepsiptera and Physopoda all the hooks are wanting. The 

 Diptera, and many Hymenoptera have moreover under these hooks softl obules {arolia) 

 provided with numerous small papillse, by meansof which these insects can fix themselves 

 to objects." 



To this, the editor of the American edition adds : — " The Tenthredinidte have a lobule 



of this kind on each of their legs, and the Diptera have even two to three." 



*' According to Blackwall the papillse of the arolia secrete a viscid siibstance, which enables 

 the Insecta having these organs to walk on smooth and steep surfaces. But this assertion 

 requu-es further proof, though admitted by Spence." 



It must not be imagined that the above is a correct representation of the knowledge 

 possessed in this country on these structures. Not one statement is quite correct. Thus — 



1. The structure of the tarsi in the Curculionidse was correctly described nearly two 

 centuries ago ; they do not grapple objects by means of the immoveable hooks on their 

 tibiae, chiefly, but by their tarsi, in which action the former will of course sometimes bear 

 a part, but even then only a very subordinate one. 



2. The feet of the Strepsiptera and Physopoda differ so essentially that a comparison 

 instituted between them solely on the ground of the presence or absence of claws cannot 

 be considered a happy one. The tarsal joints of the Strepsipterous feet somewhat re- 

 semble a series of fly's pulvilli strung together ; a dense brush of haii's covers the under- 

 surface of the joints. The legs of the PhysojDoda are terminated by minute, naked 

 bladders. 



3. The comparison between the feet of Diptera and of Hymenoptera is equally unfor- 

 tunate. The structure of the former had been, as I have shown, repeatedly described with 

 a near approach to accuracy, even before Blackwall's observations ; the latter was, I 

 believe, correctly described for the first time by myself. Tlio observations will be given 

 in a future communication. 



4. The Tenthredinidaj are Hymenoptera, with the type of foot of their Order, and with, 

 in addition, small cushions underneath each tarsal joint ; which peculiarity, though it at 

 once attracts the attention of any one who looks carefully at the feet of an example of this 

 genus, is not mentioned by the editor of the work in question. 



About the same time a series of brief descriptions of the microscopic structure of Insects' 

 feet was published by Dr. Inman*, who describes the feet of not less than thii-ty-one 

 species of Articulata, mostly of the order Insecta. Allusion Avill have to be made to these 

 remarks presently ; from the figures given, I judge that many of the descriptions were 

 made from preparations of the parts, mounted as " objects for the microscope." These 

 are selected for their beauty alone ; and, from the way in which they are prepared, it not 

 unfrequently happens that they tend to convey ideas of structure and relations of a very 

 erroneous nature. I gladly bear my testimony to the real merits of this paper, and to 

 the benefit I have derived from the suggestive nature of many of tlie remarks in it ; at 

 the same time an expression of regret cannot be Avithheld, that the illustrations are so 

 unworthy of the remarks to which they are appended. 



* "On the Feet of Insects," by Thomas Inman, M.D., 8vo., pi. 10, Proceedings of the Liverpool Literary and 

 Scientific Society, No. 6, 1851. 



VOL. XXIII. 3 I 



