18 Dr. F. Miiller on the Development of the Stomapoda. 



the raptorial feet there is a small, roundish, laminar or vesicular 

 appendage. 



The raptorial feet are followed by six segments destitute of 

 appendages : of these the three anterior, which are covered by 

 the carapace, but not amalgamated with it, increase in length 

 backwards in the proportion of about 2:3:4; taken together, 

 they are half the length of the three posterior ones, which are 

 equal to each other. The six rings together are 0*75 mill, in 

 length ; their breadth is 0'2 mill. 



The following five segments, which together make up fully 

 one-fourth of the length of the body, are about one-half broader, 

 somewhat constricted at the articulations, and each armed at its 

 posterior angles with a short spine. The four anterior of these 

 five segments bear natatory feet (fig. 7), which ai'e all constructed 

 in the same manner : — a large basal joint, 0'3 mill, in length, 

 and somewhat dilated at the extremity, bears two terminal la- 

 minae of about half that length, and beset with bristles ; of these 

 the inner one has a small finger-like process towards the end of 

 its inner margin. The branchiae are still entirely wanting. 



The tail, consisting of a single piece, forms a large quadran- 

 gular lamina of about one-fifth the length of the body, and 

 scarcely less in breadth ; its lateral margins are gently arched, 

 and its hinder margin slightly emarginate ; sixteen minute 

 denticles stand in this emargination, a somewhat longer one at 

 6ach posterior angle, and six on each lateral margin. 



The only Stomapod with which I am acquainted here is a 

 Squilla, differing little, if at all, from S. Mantis. The larva de- 

 scribed will probably belong to this. Young Squilla of the 

 same species, of about 10 mill, in length, are already exactly 

 similar to the mature animal, except in the smaller number of 

 joints in the antennae, of teeth on the raptorial feet, of branchial 

 filaments, and the like. They had still the glassy transparency 

 of our larva, and possessed like it a median eye. 



EXPLANATION OF PLATE II. 



Fig. 1 . Zoea form * of a Stomapod from the Sea of Santa Catharina ; 



magnified 15 diameters. 

 Figs. 2-7. Different parts of the same ; magn. 90 diam. 



2. Anterior part of the body, from below. 



3. Anterior antenna, from the side. 



4. Mandible. 



5. Anterior maxilla. 



* I would extend the name of Zoea to all larvae of Crustacea possessing 

 two pairs of antennae, three pairs of buccal organs, and two or three pairs 

 of legs on the thorax, but still destitute of the five or six last pairs of 

 thoracic feet. 



