NO. 1772. ANNELIDS OF THE ARENICOLIDJJ^—ASHWORTH. 



29 



characters of crotchets from examples of different ages have been 

 adequately studied only in one species of Arenicola, namely, A. 

 marina. Judging from the characters of the crotchets from specimens 

 of A. marina of different sizes, the two small crotchets above de- 

 scribed are such as one would expect to find in a young worm not 

 more than about 20 mm. long. Most of the crotchets of this worm 

 would, after becoming worn, be grad- 

 ually cast out and replaced by others 

 of a slightly larger size, and this proc- 

 ess has no doubt been repeated several 

 times, but for some reason these two 

 crotchets have escaped being cast out 

 and remain among the bases of the 

 crotchets formed at a much later 

 period than they were, for the worm 

 must have been, at the time of cap- 

 ture, about 70 mm. long. 



Nephridiopores are visible on the 

 fourth to the ninth segments, inclu- 

 sive, in specimens Nos. 1 and 2. 

 These apertures have the usual posi- 

 tion on the segment, i. e., near the 

 upper end of the neuropodium. 



Ova were found escaping through a 

 rupture in the body wall of specimen 

 No. 1. The diameter of these ova is 

 nearly 0.2 mm. 



In two specimens the pharynx 

 ("proboscis") is protruded; it is cov- 

 ered with papilla. Those of the re- 

 gion first everted are conical in form. 

 Those of the portion everted later are 

 much smaller and rounded at their tip. 



The internal organs of fragment 

 No. 3 have been examined, but they 

 are very badly preserved, and there- 

 fore only a general description of 

 them can be given. 



The alimentary canal presents the usual regions — pharynx, oesopha- 

 gus, and stomach. There is a single pair of oesophageal glands ; each 

 gland is somewhat conical in form and about 5.5 mm. long. 



Projecting backwards from the first septum, ventro-lateral to the 

 point at which the oesophagus pierces it, there are two thumb- 

 shaped pouches, 2.0 and 2.5 mm. long, respectively. 



A. B. 



D. 



Fig. 1-1.— a. glaculis, neukopodul crotch- 

 ets. A AND B WERE FOUND TOGETHER, 

 THE CROTCHET B "WAS IN USE, A IS ONE OF 

 THE TWO SMALL CROTCHETS FOUND IN THIS 

 NEUROPODIUM. FOR FURTHER REMARKS ON 

 THESE, SEE TEKT. A AND B ARE FROM NO. 



6, X300, C FROM NO. 7, X300, D from no. 

 3,X150. 



