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Show 1892.] FROM ALGERIA AND TUNISIA. 29 rich, though at present but little known ; but the Sahara has here, as it has in the case of other animals, to be a barrier preventing the northward range of these forms. Only in Egypt are there any genera found also in Tropical Africa ; the very remarkable genus Siphonogaster occurs in Egypt and in the neighbourhood of Lagos, W . Africa. But the banks of the Nile, or even the river itself (for many species of Earthworms can withstand a prolonged immersion in fresh water), have furnished, no doubt, the opportunity of migration. Mr. Alvan Millson, Colonial Secretary at Lagos, kindly collected for me a number of Earthworms in Egypt; all these species were members of the genera Lumbricus and Allolobophora. Besides Levinsen's paper upon Siphonogaster and Digitibranchus {:=Alma) we do not possess, I believe, any further information upon the Oligocheeta of Egypt than that which has been given in the preceding sentence. Dr. Anderson's collection contains examples of two recognizable species, Allolobophora complanata and Microscolex modestus. Besides these, there are two or three immature forms of the genus Allolobophora which are not old enough for identification. ALLOLOBOPHORA COMPLANATA (Duges). Lumbricus complanatus, Duges, Ann. Sci. Nat. t. viii. pp. 17,22. This species is a well-known South-European form, having been met with in S. France, Italy, Portugal, and the Balearic Islands. I now add Algeria to the list of localities whence it has been obtained. The principal information as to the structure of this species is to be found in Duges's memoir upon the Earthworm, in Rosa's account of the Lumbricidse of Piedmont \ and in a paper by myself devoted to this species 2. In neither of two specimens belonging to Dr. Anderson which I dissected was there any trace of the peculiar diverticula of the spermathecse which I described in the paper last referred to. As neither Duges nor Rosa observed anything of the kind, it is possible that the individual I described should be regarded as a variety of the more typical form, the occurrence of which in Algeria I here record. MICROSCOLEX ALGERIENSIS, n. sp. There is only a single specimen of this species, which I investigated by means of longitudinal sections of the head end. The structure of the posterior segments was examined by mounting portions of the body in glycerine after having been cut open. It is a small worm, measuring only an inch or so in length and composed of 80-90 segments. Being curled into a circle in the preservation, I am not able to give exact measurements, which are, however, not of very great importance. 1 ' I Lumbricidi del Piemonte,' Turin, 1885. 2 " Observations on the Structure of Lumbricus complanatus, Dug.," Proc. Roy. Soc. Edinb. xiii. p. 451. |