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Show 1901.] AND ARRANGEMENT OF EARTHWORMS. 205 fact that in T. incommodus there are the two pairs of sperm-sacs of many Megasoclex and Megascolides in segments ix. and xii., which Dr. Michaelsen has thought to be the primitive arrangement of those sacs among earthworms. That species also combines with this divergence in structure a peculiar disposition of the spermathecal diverticula, which are not arranged in a pair of trifid or multifid appendages as in other species, but in a continuous circle of sacs round the spermatheca. W e may perhaps regard this form as the starting point of the genus, the other conditions being arrived at by a loss of one pair of sperm-sacs and a reduction of the spermathecal appendages. It is to be remarked that in other species the sole remaining pair of sperm-sacs has increased in size, which may be connected perhaps with the disappearance of the anterior pair. The following is a complete definition of the Genus TYPHOEUS Beddard. Small to moderate-sized earthworms, with 8 setae per segment arranged in couples. Prostomium large. Clitellum occupying segments xiii.-xvii., partly or entirely. Male pores very conspicuous and upon segment xvii., corresponding in position to ventral setae. Spermathecal pores upon the interval vii./viii. Genital papillae one to six pairs upon clitellar and neighbouring segments ; rarely absent (?). Dorsal pores present. Gizzard single in viii.; one pair of calciferous glands in xii. Intestine furnished with six pairs of glands beginning at about segment lxxx. Excretory organs micronephridia. Dorsal vessel single. A single pair of testes, funnels, sperm-ducts, and (except in T. incommodus) sperm-sacs. Spermiducal glands tubular, with penial setae. Spermathecae one pair with one or two diverticula, or more. Hab. India, Ceylon, Burmah. The seven species may be thus briefly characterized:- Typhoeus orientalis. T. orientalis Beddard, Ann. Nat. Hist. (5) xii. p. 219. Length about 100 m m . Genital papillae between segments xiii./xvii. and xviii./xx. in line with ventral setae. Spermathecal pores corresponding to ventral setae. Spermathecae with two small and trifid diverticula. Penial setae with chevron-shaped striae at free end. Hab. Neighbourhood of Calcutta. Typhoeus gammii. T. gammii Beddard, Quart. Journ. Micr. Sci. xxix. p. 111. Length 250 m m . Genital papillae single and elongated between xix./xx., xx./xxi. Setae paired ventrally, farther apart in lateral |
