70 ME. F. E. BEDDAED ON THE ANATOMY AND 



Microchceta ; in TJrocliceta and other Earthworms 1 where the nephridium opens upon 

 the same series of setse as the copulatory pouch, the latter has no such rudiment, which 

 is exactly what would be expected on this hypothesis. 



Another fact, which is of some importance from this point of view, is the condition 

 of the spermathecse in Ocnerodrilus 2 as diverticula of the vas deferens. 



I am of course quite aware that this is very hypothetical, and I merely make the 

 suggestion for what it is worth. 



In any case it is interesting to notice that the structures which no doubt function as 

 spermathecse are placed behind the testes ; it is invariably the case in other Earthworms 

 that the spermathecae lie anterior to, or at most in the same segments with, the testes. 



Circulatory System. 

 The circulatory system of Microchceta presents some peculiarities which, so far as I 

 am aware, have not been recorded in any other Earthworm except Megascolex cceru- 

 leus z . The dorsal vessel, instead of being a simple tube, is composed of two distinct 

 tubes only fused here and there ; on PL XV. fig. 2, is a drawing of other dorsal and 

 ventral vessels, together with the connecting hearts, slightly diagrammatic. The dorsal 

 vessel, in segment three, is a simple tube ; in the succeeding segment it is double, but the 

 two halves are closely bound together, and only recognizable as distinct by the presence 

 of two quite separated blood-clots lying side by side in the apparently single tube ; at the 

 hinder margin of the segment a pair of transverse vessels unite the dorsal with the 

 ventral blood-vessel ; in segment five the dorsal vessel divides immediately after passing 

 through the mesentery into two separate tubes, which unite at the posterior end of the 

 segment into a much dilated receptacle ; with this are connected the two pairs of 

 hearts of the segment ; in the following segment, that which contains the gizzard, the 

 dorsal vessel again splits into two halves, which are widely divaricated, but meet and 

 fuse together before giving off the pair of hearts ; the arrangement of the vessel in 

 segment seven is precisely similar. In the next segment the dorsal vessel is apparently 

 simple, and forms a very wide chamber, at least double the width of the same vessel in 

 the preceding or succeeding segments ; on slitting it open, however, it was found to be 

 divided by a longitudinal septum reaching nearly as far as the posterior extremity; at 

 this point the septum disappears, and the cavity is single ; the exit of the two " hearts " 

 is guarded by a valve on either side. In the two succeeding segments the dorsal vessel 



1 EudrUus appears to form an exception to this rule ; but the structures described by Perrier as copulatory 

 pouches are altogether so anomalous, that their correspondence with the copulatory pouches of other Earth- 

 worms cannot be regarded as certain, as Perrier himself implies. 



2 Eisen, Nova Acta Soc. Peg. Sci. Upsala, vol. x. 



3 P. E. Beddard, "On the Anatomy and Histology of Plei<roc7iceta," Trans. Eoy. Soc. Edin. vol. xxx. p. 481. 

 This genus is really identical with Templeton's Megascolex. At the time when I wrote I had not seen the 

 type-specimens and Templeton's description is too vague to be of any use in recognizing the worm. 



