TABLE OF CONTENTS. 



Introduction, 274. 

 Coefficient of net, 278. 

 Temperature : 



Methods, 286. 



Results, Winter, 289. 

 Spring, 291. 

 Summer, 293. 

 The Thermocline, 295. 

 Autumn, 299. 

 Annual distribution of the Crustacea : 



General account, 301. 



Winter, 305. 



Spring, 307. 



Summer, 309. 



Autumn, 311. 



Table of Crustacea, 313 . 



Order of succession of leading species, 316 . 



Largest numbers per cubic meter, S18. 

 The species in detail : 



Diaptomus, 319. 



Cyclops, 326. 



Epischura, 332. 



Ergasilus, 333. 



Nauplii, 333. 



Daphnia hyalina, 335. 



D. pulicaria, 340. 



D. retrocurva, 345. 



Diaphanosoma, 347. 



Chydorus, 348. 



Leptodora, 350. 

 Factors determining numbers of Crustacea : 



Food, 352. 



Temperature, 358. 



Competition, 365. 

 Horizontal distribution ; swarms, 366. 

 Vertical distribution, 375. 



Winter, 378. 



Spring, 380. 



Summer, 382. 



Autumn, 386. 

 Vertical distribution of individual species, 

 391. 



Diaptomus, 394. 



Vertical distribution of : 

 Cyclops, 395. 

 Daphnia hyalina, 397. 

 D. pulicaria, 399. 

 D. retrocurva, 402. 

 Diaphanosoma, 403. 

 Chydorus, 404. 

 Leptodora, 404, 

 Nauplii, 405. 

 Distribution in the upper meter; diurnal 



movement, 407. 

 Distribution at the thermocline, 415. 

 Factors determining vertical distribution : 

 Food, 419. 

 Temperature, 421. 

 Chemical condition of water, 423. 

 Light, 425. 

 Wind, 427. 

 Gravitation, 429. 

 Age, 431. 



Specific peculiarities, 432. 

 Literature, 433. 

 List of plates, 435. 

 Statistical tables : 

 Dates of collections, 436. 

 Average number of Crustacea per cub 



meter, 437. 

 Average number and percentile vertical 



distribution, 438. 

 Diaptomus, numbers and vertical distri- 

 bution, 439. 

 Cyclops, numbers and vertical distribu- 

 tion, 441. 

 Daphnia hyalina, numbers and vertical 



distribution, 442. 

 D. pulicaria, numbers and vertical dis- 

 tribution, 444. 

 D. retrocurva, numbers and vertical dis- 

 tribution, 445. 

 Diaphanosoma, numbers and vertical 



distribution, 445. 

 Chydorus, numbers and vertical distri- 

 bution, 446. 

 Index, 447. 



