FAMILY ZYGiENID^E. 9 



what is typical.) This is without doubt the most isolated group 

 in the whole family. If we step higher or lower we find 

 changes of form introduced which, slight as they are, detract 

 from the singleness of the type. Bombyx mori the silk-worm, 

 stands next above, in the adjoining subfamily Bombycinse. 

 But the larva is greatly elongated, with a slight tubercle on 

 the end of the body, being in fact sphingiform. The moth has 

 short narrow falcate wings, which are no longer than the body. 

 Attacus has falcate wings, but they are very broad and are 

 three or four times the length of the body, while the larva is 

 short, large and plump. The next step below is Tropcea 

 Luna Hiibner. This is colored green and the hind wings are 

 ' : tailed." The family color is brown, not green, and the 

 "tail" is borrowed from Papilionidse, Lycsenidaa and Phal- 

 sEenidas. If we descend further down in the scale we find 

 Hyper chiria In Walker, possessing manifest analogies to 

 Clisiocampa in the elongated body of the larva, the pupal form 

 and the outlines of the imago. 



The genus Eudryas stands at a nearly equal distance from 

 the beginning and end of its group, and is still loaded down 

 with features which are so unlike Alypia to which it is in reali- 

 ty closely allied, that Harris refers it to the Notodontians, 

 though fully acquainted with its larva, and Walker refers it to 

 the Noctuidas. Its coloration is most deceptive, since the 

 species instead of being blue or green, are white with yellow, 

 green and purple markings. The body is unusually hairy, the 

 antennge are filiform as in the Noctuidse, the legs tufted as in 

 Pygcera, Daiana and allies, and the metallic scales on the 

 thorax are only found so far as we know in Tolype. 



The first attempt to group the Eabrician genera Procris and 

 Zygsena was that of the authors of the Wiener Verzeiclmiss* 

 in 1801. They divide the Linnsean genus Sphinx into seven 

 groups of which the last, "G," " Sphinges maculates" com- 

 prises the Zyg83nida3, thus making it equivalent to all the 

 iEgeriadse, and to any one of their five groups of the true 

 Sphinges, i. e- the genera Sphinx, Smerinthus, &c. 



* Syst. Verz. der Schnietterlinge Wiener Gegencl. Illiger's ed. Wien. 1810. 

 Vol. i, p. 88. 



ESSEX INST. PROCEED. VOL. IV. B. 



