312 BULLETIN OF THE 



Just behind the eye-stalks, on the front part of the carapace, arc two 

 large blotches of dark pigment. Two similar pigment-spots are seen in 

 most individuals on the hinder part of the carapace, and one in the 

 median line of the body on the dorsal side of the second abdominal seg- 

 ment. The distribution of pigment-spots varies considerably, however, 

 in ditferent individuals. 



Second Larval Stage (PI. II. Figs. 2-4). — After the first moult the 

 larva measures 3 mm. from the tip of the rostrum to the end of the 

 abdomen. It now has the the same general shape as in the preceding 

 stage, but the carapace is provided with a dorsal spine which is directed 

 forward at the base of the rostrum, and a lateral spine on each side, on 

 the anterior margin. This spine is the supra-orbital of Stimpson's 

 nomenclature.* The posterior margin of the fifth abdominal segment is 

 produced into a tooth-like process on each side. 



The first pair of antenna) have acquired an additional (third) segment, 

 but are still simple. 



The second pair of antenna are of the same shape as in the first 

 larval stage, as are also the mandibles and maxilla). 



The maxillipeds have increased in length, and the second and third 

 pairs are longer in proportion to the first pair than they were in the 

 foregoing stage. The first pan- have gained a segment in both the inner 



Ailer. Kongel. Dansk. Vidensk. Selsk. naturvid. og mathera. Afhandl. IX Deel, 

 pp. 245-251, Tab. VI. Figs. 120-132. 1849), the young of Hijipolyte polaris ex- 

 tracted from the egg have the five pairs of walking-feet in the form ol" small, simple, 

 jointed a])pendages, the first pair with the chela already formed. Five pairs of 

 double abdominal limbs are also present, but no sign of the sixth or ]iostcrior pair. 



"We thus see amoTig the Caridca a very great difference in the degree of develop- 

 ment in whicli the larvne leave the egg. At one extieme we have Pcncvs quitting 

 tlie egg as a nauplius (Fritz Miiller, Die Verwandlung der Garneelen. Arch. f. 

 Naturg., Vol. XXIX. pp. 8 - 23, Taf. II. 1863), at the other Hippobjle, provided with 

 all the appendages of tlie adult excepting the last abdominal. Here the walking-feet 

 are simple from the first, and the larva does not pass through a Schizopod stage. 

 IJctween these extremes are larvjE like those of Caridina (Joly), Palccmmietes, etc., 

 whicli hatch with appendages developed as far back as the third i)air of maxillipeds 

 inclusive, or the second pair of walking-feet, and which pass through a Mijsis-statc. 



It is to be observed, however, that in the larva doubtfully referred to Hiirpolyle by 

 Claus (Untersuchungeii zur Erforscliung der Genealogischen Grundlage des Crustaceen- 

 Systems, pp. 44, 45, Figs. 14-18. 1876), the rudiments of the walking-feet appear 

 subsequently to the earliest larval stage, — first the two anterior pairs simultaneous 

 with the swimmerets (the earliest to appear of the abdominal limbs), then the three 

 following i)airs. Here all the walking-feet of the adult are split-feet in the larva. 



* Prodromus Descriptiouis Animalium Evertebratorum, etc. Proc. Acad. Nat. Sci. 

 Phila., ISGO, p. 24. 



