1902.] 



A NEW ORGAN IN AN EARTHWORM. 



167 



out later that there are somewhat similar cavities in, at any rate 

 one other genus of earthworms. The naked- eye features of these 

 organs was not unsuggestive of " coelomo- ducts " ; they are plainly 

 part of the coelom still, opening into it by a wide mouth and 

 narrowing towards an opposite extremity. Naturally, therefore, 

 the existence of any oiifice on to the exterior of the body was 

 carefully sought for. We have satisfied ourselves, however, that 

 there is no external pore directly connected with these open sacs. 

 Otherwise they suggested to us the "brown funnels" or "atrio- 

 coelomic funnels " of Ainphioxus, discovered by Lankester \ which 

 coexist in that animal with another kind of excretory organ, just 

 as do the present structures with nephridia of the usual " peri- 

 chsetous " type. And it may further be remarked, that in the 

 brown tubes the shape is much the same, though the wide opening 

 is into the atrial cavity (?'. e. the exterior). There is, however, as 

 already stated, no visible and direct external orifice to these 

 funnel-shaped tubes. But they enclose abundant nephiidia, and 

 of these we have ascertained external pores. So that after all the 

 cavity of the coelomic pouches does communicate with the exterior. 

 It is conceivable that we have here a state of affairs com- 

 pai'able to that seen in certain Polychasta wheie, according to 

 Goodrich ^, coelomic funnels become secondarily connected with 

 trvie nej)hridia. In Pheretima this connection is obviously vague 

 and loose ; but it may be, so to speak, a preparation for a closer 



Text-fie-. 38. 



Transverse section through body-wall and underlying coelomic pouches of 

 Flieretima posthuma. 



E, epidermis ; C.S, coelomic pouch ; M, M', muscular layers of body-wall. 



relationship. The microscopic structure of the walls and contents 

 of these series of pouches has given no fui'ther clue to their 

 morphological meaning, nor to the part which they play in the 

 economy of the Annelid. The drawing exhibited (text-fig. 38) 

 shows a longitudinal section through the couple of pouches of one 

 side of the body, the " waist " or junction of the two being 

 naturally in the middle. The walls are simple, composed of an 



1 "Contributions to the Knowledge of Amphioxus lanceolatiis ," Quart. Journ. 

 Micr. Sci. xxix. p. 394. 



2 Goodrich : " On the Nephridia of the Polychaeta," ibid. xli. p. 439. 



