148 PROCEEDINGS : BOSTON SOCIETY NATURAL HISTORY. 
cean development, and in the year 1840, two papers on Pagurid 
development appeared. One of these (Rathke, ’40) deserves to stand 
as the first real contribution to our knowledge of the metamorphosis 
in this group. For Thompson did not describe his larva and 
Philippi’s paper of the same year merely figured in a rough way 
the first zoea. Rathke’s paper, however, briefly described three 
zoeal and a Macruran like older stage of the European “ Pagurus 
bernhardus .” Two years later (Rathke, ’42) it was republished in 
more complete form with excellent figures of the zoeae and of the 
maxillipeds, tail fan, and pleopods of the “older larva.” 
Then twenty years passed without any important addition along 
this line of carcinological research until the publication of Muller’s 
“Fur Darwin,” in 1864. This article described a “Pagurus” zoea, 
called attention to the absence of any gradation in the successive 
zoeal stages towards the Macruran-like stage, and, although it is 
uncertain whether Muller actually saw this later stage, it is described 
and compared to a small shrimp which had received from Milne- 
Edwards the name Glaucothoe. “ Glaucothoe peronii may be such 
a young, still symmetrical Pagurus.” The recapitulatory nature of 
the stage is also asserted. “ The abdomen is truly in the adult a 
clumsy [ungeschlachter] sac, filled with liver and sexual organs, but 
it is yet fairly powerful [kraftig] in the glaucothoe-stage and it was 
also still stronger when this stage was the permanent form of the 
animal.” 
A few years after Muller’s article appeared, Spence Bate (’68) 
published an account of two zoeae and a glaucothoe which he col¬ 
lected at the surface and correctly assigned to “Pagurus.” Of the 
latter stage he says: “ In this they probably continue until they find 
a suitable molluscous shell. ... I imagine that they may cast their 
exuvium and grow during the whole time that they are deficient of 
such a shell because I have taken specimens, occupants of shells, 
that were still smaller than the ones described and yet further 
advanced toward maturity. It would be curious to see if, were they 
deprived entirely of a shell as a habitat they w T ould continue to grow 
and retain the normal [i. e., symmetrical] form of the pleon gener¬ 
ally.” 
This query as to the effect of depriving the young of a shell was 
in part answered by Agassiz (’75) nearly ten years later. He 
showed that the larva might attain asymmetry and a soft abdomen 
