Mabch e, 1895.] 



SCIENCE. 



205 



number of eggs recorded for lobstei-s of this 

 size show that thei-e is a tendency to main- 

 tain this higli standard of production even at 

 an advanced stage of sexual life. 



A graphic representation of the fecundity 

 of the lobster tells more forciblj' than words 

 or figures can do ho^^■ closely it conforms to 

 the law just enunciated. The curve which 

 we obtain is the wing of a parabola; the 

 curve of fecundity is parabolic up to the 

 fourth term, where the ratio of production 

 is distinctly lessened. The largest female 

 lobster, carrying the largest number of eggs, 

 was obtained at No Man's Land, June 9th, 

 1894. It was sLsteen inches long and car- 

 ried one pound of eggs, estimated to contain 

 97,440. It is safe to assume that the aver- 

 age number of eggs laid by a lobster eight 

 inches long is not above 5,000. The large 

 lobster just mentioned, on account of the 

 incumbrance of its eggs, M'as unable to fold 

 its 'tail,' which suggests the explanation of 

 the rudimentary condition of the first pair 

 of swimmeretts. If these appendages were 

 of the average size the large number of eggs 

 which would naturally adhere to them 

 would make folding of the abdomen impos- 

 sible, and it is by folding the 'tail' that the 

 egg-bearing lobster so successfully protects 

 her eggs and eludes her enemies. 



Period of Incubation. — Summer eggs which 

 are hxid in July and August are ordinarily 

 hatched in June, after a period of from ten 

 to eleven months. Xothing is known about 

 the hatching of fall and winter eggs. The 

 majority of the eggs which are hatched at 

 AVood's IIoU complete their development in 

 June. 



That young are liatched at other times is 

 certain, and we should expect this to be the 

 case from the variations which occur in the 

 time of ovulation. Captain Chester in 1885 

 hatched some eggs at Wood's Holl Station on 

 the 8th of November and the following days, 

 the temperature of the water varying from 

 54.3 to 56 degrees Fah. Some lobsters 



were hatched early in FeViruarj- in 1889 at 

 the hatchery of the Fish Commission Station 

 at Gloucester, Jilass. The water was very 

 cold, and it was estimated that as many as 

 10,000 lobsters were hatched. 



Period of Scrual Maturity. Lobsters be- 

 come mature when measuring from 7i to 

 1'2 inches in length. Very few under 9 

 inches long have ever laid eggs, while but 

 few have reached the length of \Q^ inches 

 without having done so. The majority of 

 female lobsters lOi inches long are mature. 

 Anatomical evidence shows that the period 

 at wliich lobsters become mature is a vari- 

 able one, extending over several years. 



Frequency of Spanning. The adult lobster 

 is not an annual spawner, bvit produces 

 eggs once in two years. This is proved by 

 the anatomical study of the reproductive or- 

 gans, and confirmed by the percentage of 

 egg-bearing lobsters which are annually 

 captured. In a total catch of 2,657 lobsters, 

 December 1st to June 30th, 1898 and 1S94, 

 the sexes were verj- nearly equally divided, 

 and about one-fifth of the mature females 

 caught bore external eggs. The catch off 

 No Man's Land in 1894 amounted to 1.518 

 lobsters; 93.59^ were females, and 1)3.7% 

 carried eggs. When these results are aver- 

 aged it is found that about one-half of the 

 females carried eggs, as would be the case 

 if they spawned every other year. Ehren- 

 baum is, without doubt, mistaken in sup- 

 posing that the lobster does not Ijreed olten- 

 er than once in four years {Der Helgolander 

 Humer, ein Gegendand deuticher Fi.icherei. 

 Aus der Biologischcn Anstalt auf Helgoland, 

 1894. 



6'((.«7)o/(VA.>. Ciastroliths are known only 

 in two Macroura. the lobster and crayfish, 

 and were observed in the lobster for the 

 first time, and recorded l)y CJeoffi-oy, the 

 Younger, in 1709. Though a dift'erentiated 

 part of the cuticle, they are not cast otV in 

 the molt, but are retained and dissolved in 

 the stomach. Their structure in the lobster, 



