ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 32 L 



migrans now proceeds to grow rapidly, to throw out roots in all direc- 

 tions, while the central tumour grows down the intestine toward the 

 junction of thorax and abdomen of the crab. At this time the adult 

 organs are differentiating in the most posterior portion of the central 

 tumour, which soon arrives at the position of evagination of the adult 

 Sacculina. Here differentiation proceeds, and the pressure of the growing 

 tumour upon the epithelium of the crab causes it to degenerate, and 

 thus when the crab next moults a hole is left in the new chitin, through 

 which the Sacculina protrudes and so gains the exterior. 



New Barnacles.* — A. Grovel makes a preliminary note on the 

 collection of stalked Cirripeds made by the German Antarctic Expedition. 

 It includes four new species of Scalpellum. 



Metamorphosis of Mytilicola intestinalis.f — Otto Pesta gives an 

 interesting account of this Copepod parasite of MyUlus gallpprovincialis, 

 in whose life-cycle are included extremes of feeding habits, from those 

 of a free life to that of parasitism. At the change of habit, swimming 

 legs are transformed into crawling ones, their now useless or even in- 

 jurious bristles becoming either rudimentary or thorny. Thorny bristles 

 may secure fixation. Similar transformations occur in the thoracic limbs. 

 A reduction of the number of segments sets in when the gut lumen of 

 the host is nearly filled up by the further growth of the parasite, and a 

 long worm-like creature results, which moves by alternate extension and 

 contraction of certain body segments. For definitive onward move- 

 ments the legs, now greatly modified, serve as struts pressing rhythmically 

 upon the gut-wall. 



Annulata. 



Metamorphosis of Echiurus.J — W. Salensky returns to a study of 

 the development of Echiurus, and gives an account of the assumption 

 of the definitive form, the differentiation of the skin, and the establish- 

 ment of the larval and adult nervous system. 



Studies on Maldanidae.§ — Ivar Arwidsson has studied a large number 

 of Scandinavian and Arctic Maldanidae, and gives an account of the whole 

 family, in which he recognises five sub-families — Luinbriclymeniaj, 

 Rhodininae, Nicomachinae, Euclynieninas, and Maldaninae. The elabo- 

 rate memoir contains descriptions of numerous new forms. 



Earthworms as Planters of Trees.|| — E. A. Andrews gives an account 

 of some observations showing that earthworms may aid in the germina- 

 tion of the seeds of at least one important kind of tree, by their habit of 

 plugging up the mouth of their burrows. On May 3 it was noticed that 

 the ground under a group of silver maple trees was covered with the 

 little key-fruits or samaras that had fallen from the trees, and in many 

 places these were collected into little heaps a foot or more apart. Each 



* Bull. Soc. Zool. France, xxxii. (1907) pp. 157-62. 



t Zeitschr. Wiss.Zool., lxxxviii. (1907) pp. 78-98 (1 pi.). 



% Bull. Acad. Sci. St. Petersbourg (1908) No. 3, pp. 307-28 (16 figs.). 



§ Zool. Jahrb., xxvi. (1907) pp. 1-308 (12 pis.). 



|| Amer. Nat., xli. (1907) pp. 711-14. 



June 17 th, 1908 z 



