ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 367 



Plankton of St. Vaast-la-Hogue.* — L. Mangin writes a report on 

 the plankton of the roadstead of St. Vaast-la-Hogue, which, with the 

 already published report of the algae of the locality by M. Hariot, com- 

 pletes the marine flora for the district. The plankton was examined 

 continually during five consecutive years, 1908-1912. The method of 

 examination has been described in a previous paper, but in the present 

 report the author corrects an error. He was led to believe that Peri- 

 dinieae were very rare at St. Vaast, but owing to improved methods of 

 examination he has now arrived at a more just estimate of their pro- 

 portion. Lists of species collected in the different months of each year 

 are given, with indications as to their number, the time of collecting, 

 temperature of air and water, weather, etc. Then follows a section 

 devoted to special observations on the different species, critical notes on 

 structure, form, distribution, etc. Almost all the hauls were made on 

 the surface, since the sea-bottom lies at a depth of not more than 

 15-20 m. below low tide, and the author did not consider that a regular 

 investigation of that depth was worth making. A chapter on general 

 observations and conclusions deals with the annual variations of the 

 volume of plankton, the variations of the succession of species, etc. 

 The volume of plankton is very poor in winter, from the end of 

 November to March or April. It then increases and reaches a first 

 maximum in May or June. A decrease takes place between June and 

 September, followed by the most important maximum in October and 

 November. The details of volume and of variation are shown by 

 means of charts, as also the occurrence of each species with its volume 

 in the different years. The author concludes that the plankton flora of 

 St. Yaast is a neritic one, formed by the invasion of oceanic forms and 

 open to the penetration of arctic or boreal species. It is a flora of bays, 

 which comprises some neritic temperate species and some arctic ones, 

 narrowly localized and become endemic, apart from any irregular 

 additions by means of currents from the North Sea. 



Microfauna of the Plitvic Lakes. f — I. Krmpotic made an exam- 

 ination of the plankton of the Plitvic lakes in September and October, 

 1912. The phytoplankton predominated over the zooplankton. In the 

 Proscansko Lake, Fragilaria crotonensis predominated markedly over all 

 other species. In the month of June only is Asterionella formosa var. 

 gracillima the most abundant. The author noticed two types, 105 \x and 

 70 jx respectively, the latter being commoner in October. Dinobnjon 

 and Cyclotetta occurred in large quantities in October. The winter form 

 of Ceratium cornutum, with three horns, was not so frequent as the four- 

 horned summer form. The number of Chroococcaceae is not incon- 

 siderable. Enough work has not yet been done to make a biological 

 classification of the lakes possible. The paper is in the Croat language. 



Colouring of Fresh-water by Algse.J — E. Naumann writes of a 

 water bloom, caused by masses of Trachelomonas volvocina Ehr., which 



* Nouv. Arch. Mus. Hist. Nat. Paris. 5 ser., v. (1913) pp. 147-241 (figs, and 

 charts). 



t Glasuik Hrvatskoga prirodosl. drustva xxv. No. 1 (1913) pp. 1-29. 

 \ Bot. Notiser, 1913, pp. 249-63. 



