CYCLOPOIDEA. 1237 



fourth pair, smaller, to the second pair of antennae. The ganglion 

 subdivides behind the oesophagus, and after continuing a short distance 

 and widening, gives off four nervous cords from each side, one to each 

 pair of natatories, the outer to the first pair; from the inner of the four 

 a branch passes from the inner side to the abdomen. The nerves 

 going to the mouth organs were not distinguished. 



The particles in the circulating fluid were not observed, even with 

 a magnifying power of two hundred diameters. 



The stomach is a large cavity, of very different shapes in different 

 species, and sometimes occupies a large part of the cephalothorax. It 

 connects with the mouth by a slender oesophagus ; it graduates into 

 an intestinal canal, without a separating sphincter. 



The genital system of the male consists of two ovoid or pyriform 

 seminal glands, united at the hinder apex, and placed nearly over the 

 mouth ; from these glands a duct passes backward to the first abdo- 

 minal segment, where it terminates in a small oval gland or mass, 

 which appears to have a corneous exterior (fig. 2 a, and /, Plate 88), 

 with the interior transparent, except a slightly obscured vermiform 

 centre. The efferent duct was not distinctly seen. 



In females, the ovaries are in the form of a branching or reticulated 

 vessel, occupying either half of the cephalothorax, and extending often 

 quite to the front margin. Besides the two main subdivisions, there 

 are in some cases, at least, two smaller intermediate branches, lying 

 nearer the medial line of the animal, and extending less far forward. 

 The eggs are often brightly coloured. 



The Sapphirinse were met with both in the torrid and temperate 

 zones, and in some regions were very abundant. Nothing can exceed 

 the beauty of some species, and especially the males. On account of their 

 extreme brilliancy and rich reflected tints they may be seen at great 

 depths on a sunny day, and as each becomes visible only when the 

 position is right for the observer's eye, the water seems to flash with 

 moving gems; they even rival the richest opal and sapphire, and 

 the most brilliant combination of metallic hues. They swim with a 

 graceful motion, often turning over and over, changing their tints, 

 and disappearing to reappear again, through their varying motions. 

 Blue is a common colour; but with this shade, fire-red, carmine, and 

 bright yellow are often commingled. Some females have a nearly 

 black colour, giving smalt blue reflections; while others are faintly 



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