48 CALIFORNIA ACADEMY OF SCIENCES. 



tulnilur network, which only gradually fuses itself into one duct with numerous 

 branching ductules, while in Lumbricus the single duct continues through the differ- 

 ent lobes and in recurring winds around itself. The tubules in Argilophilus era- 

 brace the two tubes but cease after leaving the first fold. The muscular duct which 

 is so prominent in Lumbricus is not represented in Argilophilus, but is replaced by an 

 elongation of the single wide tube corresponding to the " wide tube of the 3d lobe " in 

 Lumbricus. 



Compared again witli the nephridium of Deltania, we find that the principal 

 difference consists in the absence of the urinary l)ladder and the collar at the ne- 

 phiidio-pore as well as in the absence of a ca^cal bladder. The irregular or alternate 

 locations of the nephridio-pores distinguish Argilophilus and Plutellus from all other 

 earthworms, as far as known. 



Alimentary caunl (fig. 87 to 92). The hucml cnvitij is, as has been stated, 

 greatly eversible, and generally remains everted after the worm is dead. The 

 pliiiriin.t: is only developed superiorly though there is a slight thickening of the lower 

 wall of the buccal cavity at the junction with the (je^ophagus, at which place numer- 

 ous muscles are seen to connect with the lowei* part of the body-wall. The pharynx 

 is as usual furnished with numerous salivary glands (fig. 80, si. (jL), extending from 

 the vicinity of the brain to the posterior part of somite iv, the most posterior glandular 

 mass being the largest (fig. 8(j). The various glandular lobes offer some characteristics, 

 which if carefully noted and compared may be found to be constant enough to serve 

 as species characteristics. 



The (Esophngufi, begins in iii and occupies somites iii, iv and v, (fig. SO, ,1. tr.) 

 forming first a narrow tube, which widens out, and rising upwards connects with a 

 very large gizzard {(jz.). This gizzard occupies in reality only somite vi, but its great 

 length causes it to push far backward to such an extent that it actually occupies the 

 space covered by viii and sometimes by ix. The gizzard is compressed from above, 

 but widened laterally which makes it appear very much larger when viewed from 

 above than when seen in vertical section. It connects posteriorly, in vii, with a very 

 long narrow tubular intestine, which extends to somite xii, but which in somites xiii 

 to XV is strongly nipped by the septa and considerably enlarged (fig. (SO, s,) without, 

 however, being strictly sacculated. 



The sacculated intestine proper, however, begins first in xvi, and is much wider 

 than the other part of the alimentary canal. The structure of the pharynx offers 

 nothing of unusual interest. The wall of the gizzard contains the usual layers, but they 

 are poor in blood vessels. The longitudinal muscular layer is thickest, and on the 

 widest part of the gizzard it is five or six times as thick as the ejiithelium, gradually 

 diminishing in size anteriorly and posteriorly^ (figs. 86, 87, 88, 89). 



Pear-shaped or f^liijl us Chambers. Beginning immediately behind the gizzard, 

 and extending throughout the tubular intestine, we find imbedded between the 

 epithelial folds numerous pear-shaped organs of doubtful function. In pronouncing 



