1895,] AJS'ATOMY OF XATJTILUS POMPILIUS. 669' 



of these pass up the stalks of the follicles, and form a specially 

 developed layer immediately underlyiug the follicle-epithelium — a 

 condition to be correlated with the provision of an abundant blood- 

 supply to satisfy the needs of the glandular epithelium. 



The Testis is, in its main morphological features, quite similar to 

 the ovary ; in other words, it is an invaginated area of the lining 

 of the ccelom. Only in the testis gi-eat increase in the ai'ea of the 

 germinal epithelium has been brought about by the involuted 

 portion of coelomic epithelium, instead of remaining a simple sac, 

 becoming divided up into a system of delicate branched tubes. 



In an apparently adult specimen, the testi? was a large brownish 

 organ of roughly triangular shape, its rounded apex directed 

 upwards and towards the right side. Tts apical portion was in 

 close contact with the body-wall, while its basal part was separated 

 from the body-wall by the pericardium. 



The testis is slung up by a strong ligamentous band about 1 cm. 

 broad to the tunic of the gizzard, by a similar but broader band 

 which is attached along a sagittal line to the body-wall (the root 

 of the siphuiicle being about the middle of its line of attachment), 

 and iinally along its anterior face by a thin peritoneal fold to the 

 loop of the intestine. Further, at its lower end the epithelium 

 covering the outer surface of the testis is continued into that 

 covering the pericardial septum and heart. Near the inferior 

 angle of the organ is its aperture — a slit about 2 mm. in length, 

 bounded by two flat, much projecting lips, which, lying closely 

 opposed to one another, project into a deep recess covered by a 

 crescentic flap, the internal opening of the vas deferens. Thus, 

 though the cavities of the testis and of the vas deferens open quite 

 independently into the coBlom, they are at least during sexual 

 vaattnTity functionally continuous with one another. 



In a section through the testis of a young individual, the aper- 

 ture of the organ is seen to lead into a vestibule into which open 

 several straight ducts. Each of these, traced inwards, divides up 

 into numerous tubules which end blindly and are aggregated into 

 distinct lobes and lobules. Vestibule and tubes are lined by epi- 

 thelium continuous with that of the general ccelom. The wall of 

 the organ is traversed by a sponge-work of blood-sinuses. Between 

 the lobules these are greatly developed, their separation walls 

 being reduced to fine connective tissue-threads serving to bind the 

 lobes together. Into the substance of the lobules also pass con- 

 tinuations of the sinuses. Regarding the character of the epithe- 

 lium in different parts of the tubes, the state of the specimens does 

 not allow me to say anything. 



The Pericardium or inferior chamber of the ccelom is consider- 

 ably smaller than that already described. It immediately underlies 

 the " postero-dorsal " body-wall throughout its half next the 

 mantle-flap, and its cavity is conveniently exposed by reflection of 

 its external wall. It is then seen to be quadrangular in outline, 

 rather broader than long (68 mm. x 54 mm. in one specimen). 

 From its inner (anterior) wall, in a curved row parallel to the 



