CHAPTER II. 

 THE LIFE HISTORY OF STENOPUS, 



By Francis H. Herkick. 



This paper is the result of observatious made at Beaufort, North Caroliua, in 1881 aud 1883, 

 aud at Nassau, New Providence, in 1887. The niaiine laboratory of the Johns lIoi)kins University 

 was stationed at the latter point iu the Bahama Islands from March until July of that year, and 

 with the means thus geuerously afforded, I was able to considerably extend my studies upon the 

 Crustacea of these coral islands. 



Professor Brooks found a number of peculiar pelagic larvse at Beaufort, and it is very probable 

 that they represent a part of the life history of StenopiLs hispidu.s. Plates ix and x, illustrating 

 two important st_ages of tliese very interesting larvae, are contributed by Professor Brooks, and 

 the descriptions of these stages are based entirely upon his observations 



While the material gatliered in a sojourn of a few months at the seashore is in many in.stances 

 incomplete, it seems worth while to bring out this sketch of the Stenopns, inasmuch as nothing 

 was previously known of its development, and indeed but very little concerning the adult form. 

 IStenojjuii liispidus is, in fact, generally known to naturalists as occurring only in the Indian and 

 South Pacific oceans. It was at first quoted from the Atlantic (Cuba) by Von Martens (7) in l.S7i!, 

 and it has not since been reported from the Western Continent, so far as we are aware, until we 

 rediscovered it at Abaco, Bahama, in 188(1, but any assiduous collector on West Indian coral reefs 

 must somewhere have hit ui»on it (v. A[)pendix i). 



As the eggs are quite small, as is the case in all Crustacea with a protozoa stage, they are not 

 particularly well suited for study by means of .sections, and no special attempt has been made to 

 trace out the history of the germinal layers, a subject which can be dealt with to better advantage 

 in other species. The Stenopi breed readily in aquaria, and several series of eggs, illustrating 

 fully the segmentation, and some early phases of development were prepared, and the sections 

 were afterwards made iu Baltimore. These are given on PI. VI. They are especially interesting, 

 since the segmentation is like that of Peuicus studied by Haeckel, who relied wholly uj)ou surface 

 observations. 



The ova were immersed in Kleinenberg's picrosulphuric acid and afterwards hardened in 

 alcohol. This answered sutlicieutly well for the purpose in hand, although it rendered the eggs 

 more resistant than is desirable. 



I. — Tnii NA'4'UEAL HISTORY OF STENOPUS. 



The Bahaman Steuopus (PI. V) measures from IJ to 1^ inches in length. All the appendages 

 are long and genorallj' quite slender and delicate, especially the antenna', which give to this iVnin 

 a very characteristic appearance in the sea. These are snow-white. They are carried widespread 

 and arch outwards in graceful curves. The tlagella of the second or outer antenna! are two and a 

 half times the length of the body. In the act of swimming these are bent backward and outward, 

 while the outer division of the first or inner anteuuie is carried upward, and their inner branch is 

 diuected forward. 



The body is pure white or nearly so, excepting three broad transverse bands of reddish scarlet. 

 The first or most anterior of these color bands covers the front of the animal, involving the eyes 

 and bases of the antenuie, and in some cases it extends behind the rostrum as far as the mandib- 



331) 



