DESCRIPTIONS OF GENERA AND SPECIES 549 



according to UDE, two gizzards, paired nephridia and three pairs of spermathecae ; 

 but the male pores are stated to occupy the normal position for Acanthodrilidae, 

 and nothing is said about the dorsal vessel. 



Diplocardia communis, GABMAN. 



D. communis, GAKMAN, Bull. Illinois Lab., vol. iii, 1888, p. 47. 

 P Geodrilus singularis, UDE, Z. wiss. Zool., 1893, p. 69. 



Definition. Length, 300 mm.; number of segments, 165. Colour while living ' 'flesh-colour! 

 Prostomium not dividing buccal segment. Setae paired, absent only on XIX. Dorsal 

 pores commence IX/X. Clitellum, XIII-XVIII, saddle-shaped on last two segments only ; 

 complete anteriorly. Nephridiopores in front of dorsal setae. Gizzards two in V, VI ; 

 intestine begins in XVII. Male pores on XVIII, XX. Dorsal vessel double from 

 segment VII, the two halves uniting at the septa; last hearts in XII. Sperm-sacs in 

 IX and XII ; sperm-ducts in thickness of body-wall. Spermathecae three pairs in 

 VII IX, with a single diverticulum. Penial setae not ornamented. Hob. Illinois, 

 America. 



This species was originally described by GARMAN ; I have been able to examine 

 specimens and to confirm (adding to in a few quite minor points) his account. I 

 distinctly observed in more than one case, the duct of the nephridium perforating 

 the body-wall in front of the dorsal setae. The terminal part of the tube is not, 

 as in most Acanthodrilus, a conspicuous muscular sac ; it is, as in A. annectens, 

 a narrow glandular tube and might thus readily escape observation. The ovaries 

 seem to be unusually large ; so, too, are the egg-sacs, which are not closely related 

 to the oviducal funnel. The two spermiducal gland pores of each side of the body are, 

 as is nearly, if not quite, universal in the genus, connected by a longitudinal furrow. 

 This furrow has a curved course, the concavity being contrary to what is usually 

 found outwards. 



The spermiducal glands have, as is shown in CARMAN'S figures, a remarkable pitted 

 appearance ; white rounded masses are imbedded in a darker groundwork. They are not 

 unlike a Mammalian ovary in aspect. They are wider at the end where they suddenly 

 narrow into the duct, and extend through two or three segments. The curious 

 appearance of the glands, unlike what is found in other Acanthodrili, is due to the 

 massing of the gland cells in separate glands (as in Perichaeta), and to a corre- 

 sponding development of branches of the duct (see p. 118). 



The diverticulum of the spermathecae is attached to the long stalk of that organ. 

 The diverticulum consists of three globular, more or less separate, sacs. 



