The young of A. foliaceics and of A. catostomi, the former by 

 Jurine, the latter by Dana and Herrick, are said to quit the egg 

 after thirty five days, these appear to remain eighty days ; the tank 

 in which they were incubated was kept at the ordinary temperature 

 of a dwelling room, but receiyed very little direct sun. The majority 

 of the eggs did not hatch, nor have they at this date, Jan. 2d. I 

 today removed some from their shells and find them perfect, apparently 

 alive, and further, it seems to me that if they were dead, the fungus 

 (saprolegnia) would have attacked them; it has not, so I think the 

 larvae may yet appear. If so, it will be a case somewhat similar to 

 that mentioned by Dr. S. Lockwood in Am. Nat. 1870 page 257, "the 

 eggs of Limulus kept in a dark place hatched after 365 days; from 

 fifty to seventy is the usual time." 



The larva figured measured at the time .98 mm. in length ; 

 colorless, except the eyes, and transparent. The carapace has nearly 

 the shape of that of the adult, but is shorter, covering only the first 

 pair of natatory limbs, in the grown female the third pair is 

 covered, in the male the second ; underneath the anterior margin 

 of the shield are three rows of teeth pointing backward, also the 

 same number and arrangement of chitinous hooks as in adult 

 Argiili, viz : a pair at the base of the antennae and two pairs between 

 tlie prehensile limbs. Kroeyer regards the former as palps, but in 

 the larva they are precisely as in the adult and are evidently cuticular 

 as regarded by Clans and Thorell. 



There are clearly two pairs of antennae (fig. a', a'^), each four 

 jointed. The first pair in the adults of this genus is generally 

 described by authors as two jointed. Still the larvae of such as I 

 find figured have it of four well marked pieces ; in the course of 

 the developement the two basal joints get proportionally larger, 

 suited to prehension by means of strong hooks which appear at apex 

 and margin ;' at the same time the last two remain in about their 

 original proportion and are then regarded as an auxiliary appendage ; 

 this Kroeyer regards as the second antenna, while the true second 

 antenna he regards as a foot-jaw, but their relation and nature in 

 the larva indicates that the common designation is the correct one. 

 As regard this first pair it seems to me quite proper to regard them 

 as four jointed in the adult^^i^ certainly would simplify expression. 

 The second pair differ from those of the adult in that they are 

 twice elbowed instead of onc'?> : their form and position avo sufficiently 

 explained by the cut. 



