Nr. 1] ANATOMICAL STUDIES ON ANELASMA AND SCALPELLUM 21 



(1883); moreover, the digestive intestine, being richly furnished with 

 tufts and folds, displays a higher development than that of 

 Scalpellum. Also the digestive glands with their coarser anatoiny, 

 show a far higher organisation in Anelasma than in Scalpellum. 

 A comparison with Conchoderma gives a somewhat different result; 

 according to Gruvel (1904) the intestinal wall of the latter is no 

 doubt less strongly folded than that of Anelasma; Conchoderma, 

 on the other hand, has a great many digestive glands which 

 are, moreover, råtner distinctly diff erentiated mto hepatic, hepatico- 

 pancreatic, and paner eatic glands. Nevertheless the differences in 

 the coarser anatomy do not entitle us to speak of the rieductive 

 influence of parasitism in Anelasma. 



Very interesting results are obtained if we take as our starting 

 point for comparison a juvenile specimen instead of an adult 

 Anelasma. In the juvenile Anelasma, the digestive glands are 

 more simply constmcted, and approach those of Scalpellum; from 

 their finer struoture, they resemble the pancreatic group of glands, 

 and, moreover, display a vivid function. This stands in pronounced 

 opposition to the picture aff orded by fullgrown specimens. Although 

 the gland here as a whole is more highly developed, the structure 

 of the single gland cells nevertheless much more implies a strongly 

 reduced function. In this respect we may ithus speiak of the reductive 

 influence of parasitism. Also the finer structure of the digestive 

 intestine seerns lo point in the same direction; this may nevertheless 

 also be ascribed to the fact that all the many fullgrown speciinens 

 investigated turned out to have enipty digestive intestines. 



It may be a question, whether the latter point is of importance in 

 our judgment as to the life history of Anelasma, or in other words, 

 whether we can take the empty digestive canal as the rule or only 

 as an accident. Probably we have to lo ok on it as the common rule. 

 In this direction the reduced nature of the cirri, and the mouth 

 feet are very important points; the cirri are short and stout, and 

 even in living animals never seem to perfonm active motions. The 

 mouth feet are exoedingly reduced: the palps, and the outer 

 maxillæ, are quite rudimcntary and destitute of spines; the inner 

 maxillæ, and the mandibulæ, are very small and feebly armed. 

 Moreover the so-oalled «salivary glands» of other cirripeds are 

 wanting in Anelasma. Even though the oral part of the thorax is 

 developed into a pronounced proboscis, ils faculty as a capturing 

 organ must be very small. Taking all this together, we must 

 consider the empty digestive canal as the general rule. 



On the other hand, the active function of ovaries and testes in 

 Anelasma lays great claim to the provision of food. In Scalpellum 

 Strømii I have on extensive investigations found that only about 60 

 ova develop at a time in the mantle oavity. In cornparison with 



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