326 BULLETIN OF THE 
referred to. They relate almost exclusively to the intra-oval develop- 
ment, and for this part of the history are the completest yet made, the 
microtome having been used for getting sections of the egg in the differ- 
ent stages of its growth. 
In 1874 Anton Stuxberg published an incomplete description of the 
embryo before hatching, and of the first larval stage of Palcmon squilla.* 
In an abstract of a paper on the development of Crustacea, by Spence 
Bate, in the Proceedings of the Royal Society of London, 1876,t (the 
full paper’ has never been published to my knowledge), the author makes 
the surprising statement, that in the embryo of Palemon, etc., the 
anterior of the three earliest formed pairs of lobes (nauplius-appendages) 
develop directly into the eyes, while the posterior two pairs are cast off 
with an early moult and replaced by the permanent antenne ! 
CAMBRIDGE, June 1, 1879. 
* Karcinologiska iakttagelser. Ofversigt af Kongl. Vetenskaps-Akad. Forhandl., 
1873, No. 9, pp. 16-19. 1874. 
+ “On the Development of the Crustacean Embryo, and the Variations of Form 
exhibited in the Larve of 38 Genera of Podophthalmia.” Proc, Royal Soc. London, 
Vol. XXIV. pp. 375-379. 1876. 
I believe I have not misrepresented Spence Bate here, but will quote in full : — 
“The author has taken this opportunity of making a close examination into the 
earlier stages in the development of the embryo, and comparing the progress within 
the ovum of some of the larva that arrive at or near maturity before being hatched, 
with those of the larval forms that are hatched in a more immature condition ; and 
he states that, as soon as the protoplasm assumes anything like a definite plan, dis- 
tinct lobes, corresponding in position with those of the several appendages in the 
Nauplius, together with an embryonic or ocular spot, are present; that in the 
Nauplius forms they exist as deciduous appendages only, and are soon cast aside 
and replaced by others more adapted to the wants of the adult existence. 
“In the embryos of other Crustacea the anterior pair of lobes enlarge in size 
with little alteration of form, while the posterior two pairs are developed into 
appendages that have but a deciduous value, since they never fulfil the office of 
permanent organs, and are generally cast off with an early moult. 
“This is observable within the ovum in Palemon, Crangon, ete., and also in the 
marsupial embryo of Mysis after it has quitted the ovum. 
“The relation of these parts to the permanent organs the author has closely 
traced, and. believes that he has demonstrated that the three pairs of mobile append- 
ages in the cirripedal or Nauplius form of larva homologize with the eyes and two 
pairs of antenne, and not with the antenne and mandibles, as stated by Fritz 
Müller, Anton Dohrn, and others." 
