250 Journal New York Entomological Society. [Voi. vii. 



The three other main groups of Eucleids seem all to have origin- 

 ated in the equatorial land. The pioblem of their distribution is less 

 simple than that of the first group ; especially the colonization of 

 Australia offers difficulties. It would appear that these groups, 

 and, indeed, the family itself arose in South America, or the conti- 

 nental mass that connected South America and Africa as late as the 

 Jurassic(see Plates VII-VIII ). But I cannot inferanything verydefinite. 

 This may be largely due to the extent of our ignorance of the southern 

 species. The Megalopygida^, which are practically the ancestors of 

 the Cochlidiidai, still inhabit South America, and, according to 

 Aurivillius, Africa also, which lends support to this view. To put the 

 origin of the family back to the Triassic, when there may have been a 

 continuous continental mass reaching Australia (Plates VII-VIII), 

 would seem to give the family too early an origin, considering its 

 highly specialized larva and the condition of the flora of that period. 

 No fossils are known in the family, which precludes exact investiga- 

 tions on that basis. 



Explanation of Plate VI. 

 ■ Fig. I. CocJdidion y-inTersa, mature larva, dorsal view, enlarged. 



2. The same, last stage, but before the larva has whitened much. 



3. Sil'ine stimiilea, mature larva, three-quarters view, enlarged. 



4. Venation of Cochlidion y-inv(7-sa, illustrating the short-forked discal vein. 

 • 5. \Gna\\onoi Eitc/cn i/idctermina, illustrating the long-forked discal vein. 



6. Genealogical tree of the New York Slug Caterpillars. 



A. The main stem represents the generalized larva described above. It 

 has three rows of scarcely produced hairy warts, representing i -|- ii, 

 iii and iv -f- v of abdomen, the lower row rudimentary, and ia -f- ib, 

 iia -|- iib and iv on thorax, all three functional. A primitive first 

 stage present, the setK of the functional warts single, and modified 

 so as to be represented by thick spines, which are everted on hatch- 

 ing ; ia and ib of joint 4, i and ii of joints 5 to 12 are coalesced at 

 base. Setae of iv and v normal, fine, small, not everted. Paired 

 glandular dots representing the larger depressed spaces. Weak 

 segments 5, 7, 9 and il, shown by the less degree of erection of the 

 spines. Skin with minute secondary .spinules. Feeds in stage I. 

 Food plants various smooth leaves. 



B. The warts remain functional and are produced (hypertrophied ) 

 especially the subdorsal row ; the lateral wart of the weak segment 

 5 is lost, its spiracle moved up. Setne i and ii of stage I become 

 completely united, forming a single spine. 



C. The wnrts become succulent and easily detached, clothed with 

 differently modified hairs. Skin spinules converted into short 

 secondary hairs. Depressed spaces reduced, obsolete. 



