678 SUMMAEY OF CURRENT RESEARCHES RELATING TO 



of it found about the coasts of the North Sea. He confirms Hoek's 

 list of species, and shows that they live exclusively upon colonies of 

 hydroid polyps. His detailed observations were made in regard to 

 PJioxichilidium femoratimi, which attaches itself to the polyps of Tuhu- 

 laria larynx. He finds himself unable to agree with Dohrn as to the 

 absence of excrement, and his observations as to the genital organs also 

 differ from those of previous investigators. The female sea-spiders are 

 easily distinguishable from the males, since the latter are pale in colour 

 and greatly increased in size by the number of balls of eggs they bear. 

 Fertilisation is external. Larvae at all stages were readily procured by 

 gently pressing the polyps, and the author discusses the question as to 

 how the larvse get within the digestive tube of the polyp, and the 

 problem of the relation between the larval appendages and the limbs of 

 the adult animal. He finds that the typical protonymphon stage is 

 common to all the Pantopoda, whether it be gone through within or 

 without the egg. In the form in question a great part of the develop- 

 ment occurs within the egg. 



e. Crustacea. 



Phyllopod Studies.* — N. v. Zograf makes some notes on the struc- 

 ture of the Phyllopod ovary of which there are two types, a cylindrical 

 tube-form characteristic of the Branchiopods, and a very much branched 

 canal as occurs in the shell-bearing Phyllopods. The formation and 

 growth of the eggs, and structure and mode of formation of the egg- 

 envelopes are described. Two cases of hermaphroditism in Lepidurus 

 productus are discussed. 



New Species of Artemia.t — Vernon L. Kellogg describes a new 

 species discovered in the evaporating pools of salt works near Stanford 

 University. It differs markedly from the other American species in 

 those characteristics upon which Verrill relies to distinguish the already 

 known American forms, viz. the shape of the male claspers, the female 

 egg-sac, and the character of the caudal appendages. Size is an un- 

 reliable feature, for it varies under different conditions of density of 

 the water. In addition to a description of this new form, Artemia 

 franciseana, notes are given of differences due to varying environmental 

 conditions. Differences in the proportional length of the post-abdomen 

 to the rest of the body, in the character of the abdominal segmentation, 

 and in the length and hairiness of the caudal appendages, are apparent 

 in this new Artemia, and evidently bear a definite relation to the different 

 densities of the pools in which they are living. 



Post-embryonal Development of Caridina wyckii Hicks.| — E. von 

 Daday describes the larval stages, euzoea, mesozoea, metazoea, proto- 

 mysis, mesomysis, metamysis, and postmysis, the gradual transforma- 

 tion of the individual organs (antennae, mouth appendages, and limbs) 

 and gives a brief comparison of the course of development in a few 

 nearly related Decapod species and in Caridina. 



* Zeitschr. Wiss. ZooL, Ixxxvi. (1907) pp. 446-522 (4 pis. and 2 figs.). 



t Science, xxiv. (1906) pp. 594-6. 



X Zool. Jahrb., xxiv. (1907) pp. 239-94 (3 pis. and 1 fig.). 



