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skin, and there can be no doubt that they take nourishment through their well-developed mouth 

 (s. later on under Sphcer. danica.) They are always considerably depressed, the anterior 

 margin is long, now quite straight, now a little concave, in the younger specimens occasio- 

 nally a little convex; the lateral margins converge rather considerably backward and merge 

 more or less evenly into the posterior margin. The mouth is pretty well developed, with 

 distinct mandibles (fig. 1 g), and is situated much to the front on the ventral surface; it is 

 surrounded by rather small pouch-like processes: antennulas (a), antennae and maxillae, and 

 behind it is found a rather large, peculiar area. Near the anterior margin on the ventral 

 surface is seen a body with an irregularly curved posterior margin, and this is the adhesive 

 plate (s), by which the animal is hinged. The parts just described on the ventral surface 

 are surrounded by a naked area, whereas the greater part of the remainder of its surface 

 is provided with hairs, which are sometimes arranged in rows of two or three or more, 

 sometimes are more scattered, and the hairs which grow close to the edge are rather long, 

 the more central ones are short; the larger part of the dorsal surface is naked. Fig. 1 i 

 and fig. 1 k reveal that the contents of the pupa — perhaps on account of alcoholic influence 

 — do not reach the outer skin, whereas fig. 1 h shows a very large and entirely filled 

 pupa ; fig. 1 i, the specimen represented on a larger scale, so far shows the same as the two 

 illustrations just mentioned, but it reveals at the same time that the inner body has its 

 own skin with distinct setae at its margin. The male of Choniostoma being unknown, I 

 cannot decide how far all the specimens found are only female, or both female and male pupae. 

 We now come to a species — Sphceronella paradoxa — whose development differs 

 very much from that of Splicer. Giardii, or that of Homoeoscelis minuta, and the forms 

 which, according to my just stated (though rather defective) knowledge, are related to these 

 species. In Sphcer. paradoxa both sexes develop) themselves without passing through the stage 

 of an independent pupa properly speaking, nevertheless there is a considerable difference of 

 aspect between the development of the sexes. Let us first examine the development of the 

 nude. I had a very considerable material of larvae, which were hinged by their front, and 

 in winch the cephalothorax was nearly as broad as long, besides being very thick (pi. IV, 

 fig. 1 d) ; however, as it was impossible to me, in spite of careful searching, to find a single 

 male pupa, I conceived the idea of submitting my big larvae to a thorough examination, and 

 in a single specimen I fancied that I saw two spermatothecce through the skin. I succeeded 

 in taking away the skin of this larva, and I found a young male with hairs on its abdomen, 

 rather short caudal stylets, and two spermatothecae, whereas the limbs were still for the 

 most part rather indistinct. Hereby, then, we have got the proof that the males come out 

 directly of these big larvce (comp. Aspidoecia, p. 54), still there remains a single point which is 

 not fully explained. My rather numerous males are — with very rare exceptions — about 

 •245 and - 27 mm. in length, though one of the big larvae is only -19 mm. long, the empty 

 abdomen included, and the cephalothorax of one of the largest of these larvae is only 16 mm. 

 in length (in pi. Ill, fig. 4 c I have represented a male, in fig. 4 e such a larva enlarged on 



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