| OCR Text |
Show 214 MR. F. E. BEDDARD ON NEW EARTHWORMS. [Mar. 19, (2) Acanthodrilus occidentalis, n. sp. In point of size this is the most conspicuous of all South- American species of Acanthodrilus; about a dozen specimens in all were collected by Dr. Michaelsen, and the largest of these slightly exceeds in bulk the largest example of Acanthodrilus pictus, which is its only rival in size. The present species, however, differs from Acanthodrilus pictus in being entirely without integumental pigment, a fact which gives to it in the preserved condition a pale dirty brown colour. The worms are very soft to the touch and the segments are very much annulated. The general appearance, indeed, is like that of the New- Zealand species Octochcetus multiporus; it is very different from that of any South-American species of the genus which I have had the opportunity of examining. The sfructure, however, does not in any way resemble that of Octochcetus ; Acanthodrilus occidentalis is a perfectly typical Acanthodrilus, though differing in detail from any other species known. The largest individual at m y disposal measured 192 mm.; its diameter was at the widest point 9 m m . The number of segments of this specimen was 365. The colour of the species after death has been already referred to ; during life the colour was (according to Michaelsen) " blau grau ; Kopfende zart rosa." The clitellum during life was hardly visible; I could not detect its limits in tbe preserved specimens. The obscurity of the clitellum gave the worm a certain resemblance to many Geoscolicids. Tbe soft feel of the body is due to the minuteness of the strictly paired setae ; the setae are implanted upon the ventral side of the body ; the ventral area within the setae is to the dorsal area as 7:11. On the anterior segments of the body I could not detect the setae at all. The prostomium is continued by grooves over the buccal segment. Tbe dorsal pores commence at the eleventh or twelfth segment. The internal anatomy shows no characters of very great importance Some of the anterior septa are thickened ; this is the case with the six which immediately follow the gizzard. The gizzard, in spite of its large size, is entirely contained between the septa which bound the sixth segment. There are no distinct calciferous glands ; but the oesophagus is red and vascular posteriorly. The intestine begins in segment xvii.; it has a very rudimentary tvphlosole. The last pair of hearts is in segment xiii. The reproductive organs are like those of other species of the genus. There are two pairs of testes in x., xi.; these gonads are very much frayed out and extend right across their segments, looking as if they were attached to both walls. The sperm-sacs are of fair size ; they are racemose in form and are attached to the front walls of segments xi., xii. |
