ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 677 



Flukes from Gall-bladder of Fishes.* — Dr. M. Luke has re-found 

 Distomum capitellatum Rud. in Uranoscopus scaber, and finds that it 

 differs so strikingly from other species of Distomum that it is necessary 

 to place it in a different genus. He erects the new genus Anisoccelium 

 for its reception, and believes that it is most nearly related to the species 

 of the genus Gymnophallus. Another remarkable form from the gall- 

 bladder of Trigla lineata is described as Derogenes ruber g. et sp. n. 

 Its affinities are somewhat doubtful, but from the topography of the 

 genital organs it should probably be placed near the genus Hemiurus. 



Singapore Nemertea. f — Mr. R. C. Punnett reports briefly on a col- 

 lection of ten species, of which nine have not hitherto been described. 



In Eupolia melanogramma, the excretory system possesses, besides 

 the usual external ducts, communications with the alimentary canal close 

 behind the mouth. In E. pholidota, the excretory ducts reach back into 

 the intestinal region, thus co-existing in the same region as the gonidial 

 ducts, which seems to show that the two sets are not serially homologous. 

 In Eupolia, the lateral nerve-stems may form a commissure above the 

 anus, or below, or may not form one at all, which suggests doubt as to 

 the primitive character of this commissure. No hint of incipient meta- 

 merism was seen in the ducts of the excretory system in Lineidze. The 

 vascular system of Lineidre shows little variation in the different species. 

 The frontal organ characteristic of most Lineid© is not always present. 

 The structure of the skin is highly characteristic for each species. 



Incertae Sedis. 



Development of Phoronis sabatieri.f — Louis Roule gives a general 

 account of his observations. The segmentation of the ovum is total and 

 very nearly equal ; a morula stage is succeeded by a blastula ; a process 

 of incurving results in a gastrula ; the blastula flattens and is bent 

 upon itself ; the blastoccel remains between the protectoderm and the 

 protendoderm ; mesenchyme cells arise separately from the protendoderm. 

 The gastrula, attached to the tentacles of its parent, becomes oval, the 

 enteropore persists as the mouth, a large pre-oral lobe surmounted by a 

 cephalic plate developes, the ventral surface shows a longitudinal groove, 

 the ectoderm forms an anus and rectum and lines a short oesophagus ; in 

 short, a modified trochophore — the Actinotrocha — arises. The young 

 Actinotrocha developes tentacles, enlarges its pre-oral lobe, forms a 

 metasomic pouch, gains a posterior wreath of cilia, the blastoccel becomes 

 the ccelom, the enteron forms anteriorly and inferiorly a large ventral 

 diverticulum. The fully formed larva is then described. A period of 

 free-swimming is followed by the extraordinarily rapid metamorphosis ; 

 in 10-30 minutes histolysis and histogenesis lead to complete re- 

 organisation, the metasomic pouch is evaginated and forms the wall of 

 the body of the young Phoronis. An immediately operative factor is 

 the pressure of the ccelomic fluid on the metasomic pouch and on the 

 enteron. This cause of the metamorphosis is briefly discussed, and then 



* Zool. Anzeig., xxiii. (1900) pp. 504-9. 



t Proc. R. Soc. Edinb., xxiii. (1900) pp. 91-2. 



% Bull. Acad. Sci. Toulouse, ii. (1899) pp. 159-7«. 



