Pomona College Journal oi' Entomology 693 



tlie f|)itluli.il cells ,'is described ahovi'. In one si-ctioncd transversely, however, 

 .'iiid one lonfi'itudin.illy, .1 very remarkable variation from the norm.il was found. 

 Ill tlirsf two iiidividu/ils, there is an inner tiilie williiii llie ventriculus, with its 

 walls made up of large cells which appe.ir to he very similar to those of the 

 ventriculus. The exact origin and nature of this most extr;iordin;iry structure is 

 not yet estahlislied with cert.-iiiity. It |)(issil)ly is a contiiui.ation of the (rsopli.agus 

 into the ventriculus, hut if this is so tiu' cellular structure of the tuhe makes it 

 widely difTerent from the peritro))hic memhr.ane of H;ill)iani .and others. In all 

 c.a.ses in wliii'h the latter occurs it is not cellular ;is in the ]>resenl instance. K 

 .appears to me that the tube origin.ites from .1 later.il inx.igination of the ven 

 trieultis wall near the front end, for, to all .-ipiM-.ar.anees ;it least, it ha.s no con- 

 net'tion with the osoplijigus ;iiid is blind at the posterior end. Figure K of tlu 

 pl.ite shows this as it apj)ears to me by the examination of the sections thus far 

 m.ide. The certainty of this, however, has by no means been established and fo.- 

 that re.ason I will pa.s.s over this phase of the .inatouiy for the time being. At 

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

 be published, and it is hoped that this matter will be more; definitely est.iblished 

 Whatever this structure may be, it is an astounding thing that it should be founj 

 in a few individuals and not in others. 



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

 aliment.-iry canal. Just wli.it role the saliva plays in the digestion and the break- 

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

 role must be very important. 



The secretory system is norm.al, consisting of two small m.ilphighian tubules 

 on each side of the ventriculus. The circulatory and nervous sj'stems, also, 

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

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

 are verv thick and powerful. This might be expected from their having to swim 

 about in such a thick medium. 



A very striking peculiarity in regard to the adipose tissue is noticeable both 

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

 cavit}' immediately 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, either 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, representin 

 globules of clear animal oil. These cells show the typical reaction to the alcoholic 

 carmine stain. Their function is probabh- the assimilation of the necessarily oily 

 foods, and for that reason, no doubt, adaptation has increased their size greatly. 



An organism passing all its larval existence in petroleum, if it takes food 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 take from it whatever nutriment there is. What 

 this nutriment is is r.ither difficult to demonstrate actually. The petroleum pools 



