DESCRIPTrONS OF EARTHWORMS. 425 



same length as the penial setae , but quite different in ap- 

 pearance. The distal eutremity of these bristles (fig. 4) is 

 furnished with a conical point, forming an angle with the 

 main axis of the bristle ; beneath this point it is beset all 

 around with large, triangular spines. The situation of these 

 bristles — we may name them copulatory setae, to 

 distinguish them from the penial setae, the modified 

 bristles situated near to the male generative pores — is 

 very remarkable. On opening the worm from the dorsal 

 side , we recognize in the vicinity of each copulatory pouch 

 a large muscle (fig. 1 and 2 , m). These muscles , highly 

 developed in proportion to the muscular layers of the body- 

 wall , represent the locomotive muscle-fascicles of the ven- 

 tral bristles of segment 7 and 8 ; their proximal end is 

 not only inserted, as usual, into the proximal extremity 

 of the bristle, but is also attached to the muscular layer 

 of the body- wall in the 8th and 9th ring , not far from 

 the median dorsal line. Each muscle is flattened vertically 

 and has a breadth of l^/g to 2 m.m. ; it consists of two 

 fascicles, whose fibres do not runn in the same direction. 

 There is namely a superior fascicle, whose fibres are di- 

 rected to the ventral median line of the body , and an infe- 

 rior bundle, whose fibres are directed more forward. The 

 muscle-fibres have a lamelliform-shape and are arranged 

 radially around a copulatory bristle , which is situated ex- 

 actly in the centre of them; moreover a bundle of 4 to 6 

 similar bristles , in different stages of development , are pla- 

 ced against the posterior border of each muscle , and un- 

 doubtedly have the function of reserve-bristles (fig. 2, cb). 



Each pair of copulatory setae is accompanied by a 

 flat , band-shaped glandular body , which like a funnel sur- 

 rounds their distal extremity ; the two glands of each side 

 are connected to each other and therefore the total glan- 

 dular body has the shape of a c/3 (fig. 1 and 2 , x). 



The gland has a lobulated surface , and its internal struc- 

 ture consists , as shown by transverse sections , of a num- 

 ber of large , segregated lobes , parallel to each other and 



Notes from the Leyden ÜMuseum, "Vol. X. 



