414 SUMMAKY OF CURRENT RESEARCHES RELATING TO 



By turning about from side to side the female gives the eggs every 

 opportunity to become fastened to the pleopods. The mode of fertili- 

 sation has not been made out, but probably the sperm passes out from 

 the annul us after laying. 



A short account is given of the development. The young continue 

 to crawl about upon the pleopods for about a week after hatching, and 

 the liberated larvge return again and again to the mother. 



Sexual instincts and organs mature long before the maximum size 

 is reached. Little specimens were seen uniting in pairs when but four 

 months old and 50 to GO mm. in length, but as yet it is not known 

 that they lay before they are twenty-three months old and 75 mm. long. 



Mutations of Certain Atyids.* — E. L. Bouvier asserts that the 

 new species of Ortmannia, — 0. lienshawi recently established by M. 

 Rathbun, is a form of Atya bisulcata, which has the curious character 

 of recalling the immediate ancestral form of Atya. It is not a case of 

 ordinary dimorphism, sexual, or produced by season or locality ; in both 

 forms there are the same variations of size and sex. He considers that 

 the Atya is the direct descendant of Ortmannia, and that in the case 

 of certain species, this derivation is not yet a definitely accomplished 

 fact. Atya bisulcata and Atya serrata are in a condition of unstable 

 equilibrium, where the same creature may indifferently present the form 

 of the past or of the future. In Ortmannia americana, the primitive 

 form alone exists ; in Atya brevifrons de Man, the primitive form seems 

 to have disappeared, bequeathing a very marked stamp to its descendant, 

 which, like Ortmannia, is small and provided with locomotor feet of 

 feeble power. 



British Fresh-water Entomostraca.f — D. J. Scourfield concludes, 

 in a third paper, his synopsis of these Entomostraca. The paper deals 

 with the Ostracoda, Phyllopoda, and Branchiura, including new records 

 of rare species of Cladocera and Copepoda. A tabular statement showing 

 the distribution of the Ostracoda is given. 



Annulata. 



Regeneration of Trunk and Head Segments in Lumbricus varie- 

 gatus.J — P. Iwanow finds that the intestine in regeneration is formed 

 in the new segments of the trunk and head in a similar way through 

 the outward growth of the old intestine. In most cases the growing part 

 breaks outward through a small proctodseal, or stomodseal fold. The 

 new growing epithelium is early differentiated, and along with it there 

 are large epithelial " germ-cells," which take up a place in the ventral 

 half of the body-wall, and later on the dorsal side also. The nerves and 

 ectodermal muscles, as well as gut, are formed in essentially the same 

 way in both regions, but important differences are met with in the forma- 

 tion of the elements of the ccelomic mesoderm. In the head segments a 

 great part of the longitudinal muscles is formed through direct growing 

 in of the muscle fibres of the old trunk musculature lying near, the other 

 longitudinal muscles of the head segments along with all other mesodermal 



* Ann. find Mag. Nat. Hist., Ixxvii. ser. 7 (1904) No. 77, pp. 377-81. 

 t Journ. Quekett Micr. Club, 1904, pp. 29-44 (1 pi.). 

 X Zeitschr. wiss. Zool., lxxv. (1903) pp. 327-390 (2 pie.). 



