CHAPTER II. 



THE LIFE HISTORY OF STENOPUS. 



By FRANCIS H. HERRICK. 



This paper is the result of observations made at Beaufort, North Carolina, in 1881 ami 1883, 

 and at Nassau, New Providence, iu 1887. The marine laboratory of the Johus Hopkins University 

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

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

 Crustacea of these coral islands. 



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

 that they represent a part of the life history of Stenoims liispidiis. Plates ix and x, illustrating 

 two important stages of these very interesting larva-., are contributed by Professor Brooks, and 

 the descriptions of these stages are based entirely upon his observations. 



While the material gathered in a sojourn of a few months at the seashore is in many instances 

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

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

 Menopus hispidus 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 lS7ii, 

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

 rediscovered it at Abaco, Bahama, iu 1880, but any assiduous collector on West Indian coral reefs 

 must somewhere have hit upon it (v. Appendix i). 



As the eggs are quite small, as is the case, iu 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 1o 

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

 iu other species. The Stenopi breed readily iu aquaria, aud several series of eggs, illustrating 

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

 were afterwards made, in Baltimore. These are given on PI. vi. They are especially interesting, 

 since the segmentation is like that of Peu.Biis studied by Haeckel, who relied wholly upon surface 

 observations. 



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

 alcohol. This answered sufficiently well for the purpose in hand, although it rendered the esrgs 

 more resistant than is desirable. 



I. THE NATURAL HISTORY OF STENOPUS. 



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

 are long aud generally quite slender and delicate, especially the antenna;, which give to this form 

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

 and arch outwards in graceful curves. The flagella of the second or outer antennae 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 anteuu;e is carried upward, aud their inner branch is 

 directed 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 antenna), aud in some cases it extends behind the rostrum as far as the mandib- 



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