231 



others, and like them serving to support the body. Those of the first 

 pair, particularly, viz., those on the 2d abdominal segment, were ob- 

 served to be nearly as large and as long as the normal uncinate legs, 

 and to be retracted and then extended and applied to the surface of the 

 object on which the larva was resting, in the same manner as the pair 

 directly behind, which bear crochets ; and the same was observed as 

 regards the pair on the 7th segment. The abdominal leg on the 7th 

 segment is represented in Fig. 1 jy? planta; s a davate seta. 



To further prove to others, who might doubt whether these mobile 

 and extensile processes were really legs at all , I made careful camera 

 drawings of alcoholic specimens of the freshy hatched larva, and of 

 one after the first molt. The rudimentary legs on the second and se- 

 venth abdominal segments are seen to have a well developed planta, 

 though without crotchets, but bearing on the outside a pair of davate 

 setae just like those of the other legs. 



The occurrence of temporary abdominal appendages in the em- 

 bryos of insects in general is now well known. Wether these deci- 

 duous appendages occur in the embryos of Lepidoptera, Diptera and 

 Hymenoptera has been called in question. The figures of Kowa- 

 levsky, and of Tichomirof f, appear to prove that in Lepidoptera 

 at least such appendages do appear, though they are shorter lived and 

 more evanescent than in Orthoptera, Coleoptera etc. In his last able 

 work Vergleichende Studien am Keimstreif der Insecten, 1890 Gra- 

 ber appears to confirm Tichomiroff's observations and figures, 

 concluding in respect to Botnbyx mori as follows : Im Übrigen erschei- 

 nen sie aber den thoracalen Gliedmaßenanlagen vollkommen homotop, 

 und wäre in dieser Hinsicht auch kein Grund vorhanden, ihre 

 Homologie mit den Abdominalanhängen anderer Insecten, z. B. der 

 Käfer und Geradflügler, in Zweifel zu ziehen. (c And finally remarks : 

 ))Wenn wir also die Erhebungen der vorderen und hinteren Segmente, 

 welche jedenfalls mit denen identisch sind, die sich zu wirklichen 

 Extremitäten entwickeln, auch als Ansätze von Gliedmaßen betrach- 

 ten, so müssen wir doch unbedingt sagen, daß hier das Stadium 

 der Pantopodie nur eine ganz ephemere Dauer hat.« (p. 84.) 



We feel warrented then, in the present state of the subject to con- 

 clude that in Lagoa the crotchetless abdominal legs in question re- 

 present a persistent condition of the embryonic appendages. They are 

 certainly of some use to the insect, and thus have survived because 

 they, in a partial way to be sure, have been of service. Those on the 

 1st and 8th segments have probably disappeared from disuse. 



If these conclusions are correct then Lagoa^ in respect to its ab- 

 dominal legs, even if we do not take into account certain other charac- 



14* 



