118 



BULLETIN OF THE UNITED STATES FISH COMMISSION. 



THE RELATION OF WEIGHT TO LENGTH. 



The weights and lengths ' of 2,657 lobsters captured at Woods Hole under the 

 conditions already described (p. 25) are recorded in table 31. The weight does not 

 bear a constant relation to the length, but is very variable owing to the loss of the 

 appendages, particularly the large claw-bearing legs. These alone constitute from one 

 quarter to one-half the entire weight of the animal, and probably in the Belfast lobster 

 (plate 1), and in all giants of similar size, the weight of the large chelipeds is more 

 than two-thirds that of the entire body (see table 31ft). The lost limbs are regenerated, 

 as we have seen, but never completely so without the intervention of one or more 

 molts, so that a lobster with an undersized claw is a common occurrence. 



The weight also is subject to great variation in consequence of the molt, when a 

 dense heavy armor or cuticle is exchanged for a much lighter though larger one. In 

 the soft lobster the specific gravity of the solids and fluids of the body is considerably 

 reduced. Very few soft lobsters, however, were taken during the period of these obser- 

 vations, only about 3 per cent (see table 23), so we may ascribe the great variations 

 shown in the table below chiefly to disparity in the size of the large claws. This is 

 particularly noticeable in smaller individuals, as in the 9-inch lobsters, where out of 

 170 males the smallest weighed only 10 ounces and the largest three times as much. 



Table 31. — Relation betiveen the lengths and weights of male and female lobsters, taken in Woods Role 



Harbor, December to June, 1893-94. 



Length 



in 

 inches. 



6i 

 64 

 6| 



7 



No. of 

 males 

 exam- 

 ined. 



10 

 66 



20 

 168 



9i 

 94 



n 



10 



10^ 



10J 



104 



101 



101 



11 



HI 



llj 



11| 



12 



12J 



124 



12J 



13 



134 



14 



14i 



15 



44 

 143 

 26 



170 



32 

 148 



27 

 167 



1,313 



j No. of 

 Average Extremes! femaies 

 weight of weight j without 

 of males. ' of males j eggs ex- 



I amined. 



oz. 

 5.33 



7.60 

 10.18 



10. 40 

 11.86 

 12.75 

 15.16 



15.30 

 16.61 

 17.46 

 18.96 



19.91 

 21.24 

 24 

 24.41 



4 to 6 



11 28 



16 30 



18 30 



19 32 



27.44 ! 



28.89 



26 



29.94 



34.65 ! 



37. 20 '' 



42.36 j 



36 



43.78 



50 



50.25 



20 35 

 22 36 



48 52 



60 



74 



46 



1 



4 



47 



9 



138 



1 



29 



108 



26 



153 



34 

 145 

 26 



148 



Avera_ 



weigbtof 



females 



without 



eggs. 



8.75 

 '7.' 25 



10.76 



10 



10.25 



11.43 



12.44 



15.30 



14 



15.24 



16.36 



17 



18.61 



19.32 

 20.51 

 21.19 

 23.76 



24.63 

 27.52 



16 

 42 

 11 

 26 

 2 

 11 



24.19 

 30.48 

 32.09 

 34.46 

 34.50 

 42 



42.71 

 "47." 25 



65 



69.33 



1,176 



Extremes 

 of weight 

 of females 

 without 

 eggs. 



8 to 10 



13 



9 



8 



9 



11 



No. of 

 females 



with 

 eggs ex- 

 amined. 



21 33 

 23 41 



24 

 23 

 27 

 30 

 34 

 36 



36 49 

 40 55 



64 66 

 66 72 



Average 



weight of 



females 



with 



eggs. 



12.50 



168 



16.14 



17 



18.60 



16 



20 



20.42 



20.67 



23.86 



28 



23.12 



28.11 



26.50 

 32.10 



Extremes 



of weight 



of fern ales 



with 



12 to 13 



15 



17 



15 



21 



17 



25 



18 



24 



19 



21 



20 



28 



25 28 

 29 37 



32.25 I 30 34 



43. 67 37 



45 



Total 

 number 

 of males 



and 



females 



examined. 



7 

 1 

 7 



92 



1 



14 



113 



29 



308 



1 



73 



258 



53 



336 



1 



70 



317 



56 



351 



1 



133 



182 



1 



36 



93 



21 



41 



4 



23 



1 



11 



1 



8 



1 



1 



3 



3 



Average 



weight 



of all 



the males 



and 

 females. 



oz. 



7.29 



8 



7.57 



7.60 

 10.49 

 10 



10.36 

 11.68 

 12.66 

 15.21 

 14 



15.27 

 16.50 

 17.23 

 18.79 

 16 



19.63 

 20.84 

 22.52 

 24.08 

 28 



25. 76 

 27.66 

 26 



27.19 

 32.22 

 34.52 

 36. 37 

 35.25 

 42.91 

 50 



45.45 

 45 



49.75 

 0* 

 88 

 68 

 69. 33 



2,657 



1 The length of the lobster is measured from the apex of the rostral spine to the end of the 

 telson, not including: the terminal fringe of hairs. 



