220 



GOMPARA TIVE ANA TOMY 



CHAP. 



folds and laiuella' in such a way as to leave hardly any central free space. The 

 kidney always conininnicates by means of a ciliated canal (renal funnel or renal 

 syringe, " Nieren-Spritze ") with the pericardiimi. The position of the kidney and 

 the niorpliology of the urinary duct have already been explained (pp. 74-78). 



•"5. Opisthobranchia — Tectibranchia. — Only one kidney is found in the usual 

 position on tlie right side of the lio<ly, with the pericardium in front of it and the 

 hind-gut behind it. It is of the parenchymatous type, and is connected by a 

 ciliated canal with the pericardium. It oi)ens at the base of the gill in front of the 

 anus. 



In the rtcropada the delicate-walled kidney is not jiareiichymatous, but is a 



l'i(i. isj. -Nepbridium and pericardium of Daude- 

 bardia rufa, from above, diagram (after Plate). 1, Peri- 

 canlium ; 2, reno-pencardial aperture (renal funnel); 3, 

 iiepbridium ; 4, primary ureter ; 5, rectum ; li, secondary 

 ureter {rf. Fi-,'. 74, p. 77). 



Fio. 183.— Nephridium of Bornella (after Hancock). 

 1, Kidney ; 2, part cminectintr it with the reno-pericanlial 

 aperture (pyi-ifor)n vesicle, renal syringe) ; 3, part of the 

 liericardial wall; 4, ureter; 5, nephridial aperture. 



%W 









simple hollow cavity lined with eidthelium, and always communicates with the 

 pericardium, against which it lies. 



Nudibranchia (Fig. 183). —The kidneys of the Xudibranchia are .strikingly 

 dilierent in form from those of the Tectibranchia. The unpaired kidney is here 

 somewhat similar to the paired kidney of the Chitonida: It is a somewhat wide 

 tube (renal chamber) traversing the cavity of the body, to a greater or less extent ; 

 branches entering it from all .sides. This tube is connected at one end with the 

 jiericardium by a duct (renal syringe, pyriform vessel), which varies in length, and 

 at the other opens outward through a ureter at the base of or near the anal 

 jiapilla. 



It is said that PlcurobrancJuca, a Tcctibmnchiatc, from wjiich the Nudilu'anchia 

 may perhaps be derived, possesses a Nudibranchiate kidney. 



In Plnjllirhoe, the urinary chamber has no branchings ; it runs back from the 



