76 ME. F. E, BEDDAED ON A GIGANTIC EAETHWOEM. 



MiCKOCH^TA, gen. nov. 

 Lumbricus, Rapp, Jahresb. d. Ver. f. vaterl. Naturh.in Wiirtemberg, Jahr iv. (1848) p. 142. 



Setae arranged in pairs in four series ; clitellum occupying about twenty segments 

 (from segment ten to thirty), only developed in the dorsal region. Nephridia opening 

 in front of the dorsal pair of setse, present in all the segments of the body with the 

 exception of one or two of the most anterior; testes two pairs in segments ten and 

 eleven ; vasa deferentia opening on to eighteenth segment, not furnished with a prostate 

 gland or " penis ; " ovaries on anterior wall of segment thirteen. Alimentary canal 

 without caeca or special glands. 



Copulatory pouches represented by a variable number of small pouches (one to four 

 in each segment) in segments twelve to fifteen, opening on to the exterior in a line 

 with the nephridia and close to them. 



EXPLANATION OF THE PLATES. 



PLATE XIV. 



Microchmta raj)pi, drawn by Mr. Smit from the living worm. Natural size. 



PLATE XV. 



c, cuticle ; e, epidermis ; gl, glandular layer of clitellum ; d, dorsal vessel ; n, nephridia ; 



C.J), copulatory pouches ; m, in!, muscular layers of body-wall ; f, " testes :" g, 



gizzard ; f, dilated vascular region of oesophagus ; o, ovary ; ov, oviduct ; v, 



ventral blood-vessel ; /;, " heart ;" v.d, vas deferens ; v.d.f, funnel of vas 



deferens ; p, mesenteries. 

 Fig. 1. Dissection of Microchceta, to show specially thickened mesenteries of anterior 



region. 

 Fig. 2. Main trunk of vascular system in anterior region of body. 

 Fig. 3. Four segments in posterior region of body, to show the position and form of the 



nephridia. 

 Fig. 4. Dissection of the genital region, to show genital glands and their ducts. 

 Fig. 5. Vascular dilatation of oesophagus cut open by longitudinal incision. 

 Fig. 6. Four segments of the body which contain the copulatory pouches. 

 Fig. 7. Diagram of copulatory pouch &c. of Perichceta aspergillum, copied from Perrier 



(Nouvelles Arch. d. Museum, t. viii. pi. iv. fig. 72). 

 Fig. 8. Vertical section through clitellum to illustrate its minute structure. 

 Fig. 9. Muscle-fibres of transverse coat, very highly magnified. 



