150 THE ZOOLOGIST. 



Willis had previously written an account of these " foramina on 

 the top of the back, adjoining to each ring, supplying the place 

 of lungs." Now Willis published his work, ' De Anima Bru- 

 torum,' in 1672, so that for upwards of two hundred years the 

 pores have been known to science, to go no further back. It is 

 only in recent years, however, that they have been carefully 

 noted, and the position of the first pore recorded for the different 

 species of worm. It has been thought by some that the first 

 dorsal pore was so uniformly placed in the various species 

 of Earthworms that a specific character might be based thereon. 

 This I am disposed to think is not borne out by facts. 



Dr. Benham, one of our few English authorities on the 

 subject, says : " In many Earthworms the ccelom is put into com- 

 munication with the exterior by means of a series of dorsal pores, 

 placed on the intersegmental grooves. In Lumbricus these pores 

 occur in every somite after about segment eight ; in Digaster 

 and Perionyx they commence just behind somite four ; in Plu- 

 tellus behind somite six ; in Pleurochceta and Typhaus the pores 

 are present only behind the clitellum. They are present in 

 Acanthodrilus, and in many Pericluetce. 1 '* In Allurus they begin 

 behind segment three or four. 



As will be inferred from the foregoing, a variety of ideas 

 have prevailed respecting the use to which these apertures were 

 devoted in worm economy. Willis says they supply the place 

 of lungs, and if Derham's remarks apply to the dorsal pores, he 

 regards them simply as the openings through which lubricants 

 were poured. Lloyd Morgan is as cautious on the subject as he 

 is inaccurate. He says : " Every segment of the body except the 

 first has a dorsal pore opening into the anterior part of the ring 

 in the mid-dorsal line, and two very minute pores, one on each 

 side of the ventral line, which are the external orifices of the 

 nephridia or segmental organs, whose function is excretory." 

 The dorsal pores are not found in the typical Earthworm on 

 every segment save the first, and if they were, we are not 

 favoured by the Professor with a vestige of an idea as to their 

 use. He says : "There are no specially differentiated respiratory 

 organs, respiration being apparently effected by the surface of the 

 body," so that he does not regard the dorsal pores as lungs. 



* Q. J. Mic. Sc. 1886, p. 247. 



