VI 
ILLUSTRATIONS. 
Migration or salmon in the Columbia River: Facing page. 
Plate XXVI. (i) The two pieces of the marking button, shown separately and riveted 
together. (2) Pliers used in attaching marking buttons 134 
XXVII. (3) Photograph of eleven marking buttons after they were recovered from 
the marked fishes. (4) Photograph of converse faces of the eleven mark- 
ing buttons shown in figure 3 142 
Natural history of the American lobster: 
Plate XXVIII. First larval or surface-swimming stage of the lobster 153 
XXIX. Male lobster (Homarus gammarus) with symmetrical claws, and both of 
crusher type 276 
XXX. (1) Growth stages of lobster eggs and young, to illustrate relative sizes at- 
tained at Woods Hole, Mass. (2 and 3) Growth stages of young lobsters, 
continued 320 
XXXI. Fourth stage of the lobster 340 
XXXII. Sixth stage of the lobster 344 
XXXIII. Half section of lobster, cut in median plane, to illustrate general anatomy. 408 
XXXIV. Transverse section of body of female lobster, in plane of gastric mill 408 
XXV. (1) Left eyestalkfrom above, or what was originally the anterior side. (2 and 
3) Parts of corneal membrane of compound eye, composed of modified 
hexagonal facets of individual eyelets. (4) Left first antenna, from above. 
(3 and 6) Left second antenna, from upper and undersides. (7) Left man- 
dible, from inner side 408 
XXVI. (1) Left first maxilla of adult. (2) Left second maxilla. (3) First maxilli- 
ped. (4) Left second maxilliped. (5) Left third maxilliped. (5a and 5b) 
Transverse sectional views of three-sided meros and ischium 408 
XXVII. (1) Right toothed forceps and cheliped of female lobster, from lower side. 
(2) Left cracker claw and cheliped of female from above. (3 and 4) Base 
of great cheliped from below 408 
XXXVIII. (1-4) Left second to fifth pereiopods or slender legs of adult lobster, from 
anterior side 408 
XXXIX. (1 and ia) Left first pleopod of female and male, respectively. (2 and 2a) 
Left second swimmeretof female and male lobster, respectively. (3) Left 
third swimmeret. (4) Left fourth swimmeret from egg-bearing female of 
approximately same size as in preceding figure. (5) Left fifth swimmeret 
of series 1-3. (6) Left uropod or modified swimmeret of tail fan. (7) The 
same appendage reversed 408 
XL. Left crusher claw of lobster, partly dissected from upper side, to show rela- 
tions of muscles, nerves, blood vessels, and skin, with principal branches 
of claw arteries and nerves laid bare 408 
XLI. (1) Left second pereiopod, from anterior or upper side. (2) Shell of right 
toothed forceps in sectional view from above 408 
XLII. (1) Right toothed forceps of lobster in seventh stage. (2) Teeth from dactyl 
of lobster in fifth stage. (3) Serrate margin of jaw in area marked a, 
figure 1, embracing series i-ii. (4 and 5) Armature of index or propodus 
of right toothed forceps of lobster in seventh stage and after molting to the 
eighth 408 
XLIII. (1) Oblique section through large claw of lobster in first larval stage. (2 and 
3) Jaws of cracker claw of lobster weighing about 12 pounds. (4) Profile 
of seminal receptacle of female, from molted shell. (5) Skeleton of first 
abdominal somite of male, from behind. (6) Seminal receptacle shown in 
profile in figure 4, as seen from underside 408 
