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, 818. 

 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, 388. 

 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. 



