Pomona College Juirnal of Entomoloov 693 



tin; i-|iitluli;il crlls .'is (liscrilM-d ahovi-. In one sectioiu'd transvi-rsrly, lioweviT, 

 .■iiid one IdiigiUicliiially, a very rfiiinrkalili- variation from the normal was found. 

 In tlu'.M- two individuals, tliiTf is. an inner tulif within the vcntriculus, with its 

 walls made up of larp' cells whieh .'ippear to he very similar to those of the 

 veiitriculus. The exact origin and nature of this most extraordinary structure is 

 not yet estahlished with certainty. It possihiy is a continuatitin of the U'sophagus 

 into the ventriculus, but if this is so the cellular structure of the tube makes it 

 widely different from the i)eritro|)hie membrane of Halbi.ani and others. In all 

 eases in which the latter occurs it is not cellul.ir as in the present instance. I( 

 appears to mc that the tube originate-s from a lateral invagination of the veii 

 triculus wall near the front end, for, to all a|)peaninees at least, it has no cim 

 nection with the u'sophagus .and is blind at the posterior end. I'igure K of tin 

 plate shows this as it appears to me by the examination of the sections thus f;ir 

 made. The certainty of this, however, has by no means been established and fn ■ 

 that reason I will pass over this phase of the anatomy for the time being. .\l 

 some future time the result of further study of larger series of individuals will 

 be published, and it is hojied that this m.'itter will be njore definitely established 

 Whatever this structure may be, it is .-in .astounding thing that it should be foun i 

 in a few individuals and not in others. 



The salivary glands are large and extend far back on each side of the 

 alimentary canal. Just what role the saliva plays in the digestion and the break- 

 ing up of the oil is not known, but judging from the extint of the glands, the 

 role must be very important. 



The secretory system is norm.il. consisting of two small malj>higliian tubules 

 on each side of the ventriculus. The circulatory and nervous .systems, also, 

 present no abnormalities nor any special peculiarities worthy of note here. The 

 musculation, also, is normal as in other diptereous larva-, except that the muscles 

 are very thick and powerful. This might be expected from their h.iving to swim 

 about in such a thick medium. 



.V very striking peculiarity in n-gard to the .ulipose tissue is noticeable both 

 from examination of the entire specimen and from serial sections. The ImmIv 

 cavity innnediately within the chitinous wall is very clear and transparent, ap- 

 pearing very much as though it were gelatinous in composition. Surrounding the 

 alimentary canal and extending almost from one end of the larva to the other is 

 the adipose tissue in extremely large cells, eitlur grouped in clusters of five or 

 six cells each or sometimes chain-like in disposition. They are unusually large, 

 almost spherical in shape, with several large clear areas within each, rcprcsentin. 

 -lobules of clear anim.al oil. These cells show the typical reaction to the alcoholic 

 e.armine stain. Their function is prob.ably the assimilation of the necessarily oily 

 foods, and for that reason, no doubt, .'idaptation has increased thi-ir size greatly. 

 .\n organism ))assing all its larval existence in petroleum, if it takes fiHxl at 

 all. must of course get its nutrition in the oil. From the normal structure of its 

 mouth it is perfectly .apparent that the only way to get the nutrition is to swallow 

 the oil and let the digestive canal t.ike from it whatever nutriment there is. What 

 this nutriment is is r.itln r ditficult to d.iiionstrate actually. The petroleum piMils 



