640 THE LOBSTER-LOUSE. 



like the shed seed-vessel of some plant, and the resemblance is increased by its pale 

 green color. 



The female is considerably larger than the male, and may at once be known by the 

 black spot on each side of the abdomen. 



The CALIGUS, which is shown at fig. B, is referred to another family. 



This creature is mostly found upon the codfish and brill, and clings with great 

 firmness. Mr. Tuffen West tells me that he has examined the Caligus carefully with 

 the microscope, and assured himself that the suckers are present. " They are hemi- 

 spherical, shallow in front, where their margin thins off to a translucent membrane ; 

 and deep behind, where their concavity is bounded by a strong transversely striated 

 membrane." The figure is magnified about two diameters. 



Figs. C, D, and E represent a remarkable parasite, adherent to the gills of the lobster. 

 This creature belongs to a different tribe, which may be known by the small and mostly 

 blunt head, and the long and well-jointed antennae. The family Ergasilidae have the head 

 rounded, the body oval, the abdomen well developed, and the feet small and branched. 



The LOBSTER-LOUSE is sometimes found in considerable numbers fixed to the gills of 

 the lobster, from which the female never moves after she has once taken a firm hold, 

 though the male is more erratic in his habits, and swims about as he chooses. At fig. 

 C it is shown of its natural size among the lobster-gills, which are popularly termed 

 the " lady's fingers." At fig. D is seen a magnified figure of the female, and at E a 

 figure of the male, also enlarged. During her early youth, the female is not much larger 

 than the male, but as soon as she attaches herself to her new home, a pair of strange 

 projections are seen to grow from the side, and by degrees become so large that they seem 

 to constitute the entire creature. Below these projections the egg-sacs are developed. 



AT fig. F is seen a curious parasite that infests the sturgeon. 



The Dichelestium is rather more than half an inch in length and the twelfth of an 

 inch in breadth. This creature insinuates itself deeply into the skin, making its way 

 to the bony arches upon which the gills are supported, but not appearing to touch the 

 membranous gills themselves. Sometimes as many as ten or twelve are taken from a 

 single fish. They can grasp very firmly by means of their forceps, and are able to turn 

 round whenever they please. This curious creature belongs to the order of the 

 Lerneadae, in which the mouth is formed for suction, and the limbs scarcely visible. 

 All these beings are parasitic upon fishes, and are often so deeply buried in the tissues 

 that the whole body is concealed and only the egg-bearing tubes suffered to appear. 

 As is the case with many creatures, especially those that occupy a low place in the 

 scale of creation, the young enjoy a wider range than the parent, being able to roam 

 about at will, and not settling down to a motionless existence until they have attained 

 maturity. The figure represents the female Dichelestium. 



There seems to be no bound to the wondrous forms which these parasites assume. 

 Fig. G represents the Chondracanthus, so called because its body is covered with carti- 

 laginous spines or tubercles. The name is derived from two Greek words, the former 

 signifying cartilage, and the second a thorn. The broad and flattened egg-tubes are 

 seen below. This strange being is found upon the gills of the John Dory. 



At figs. H and I are seen two most extraordinary beings, which were discovered 

 under the abdomen of a lobster. In both these creatures (which certainly seem to 

 belong to the Lerneans), the whole of the head becomes modified into a set of branch- 

 ing fibres, much resembling the roots of a tree. There is no mouth whatever, all 

 nourishment being transmitted through these fibres. They are quite recent discoveries, 

 and after the engraving had been prepared, several of the figures were removed in 

 order to make way for forms so novel, so interesting, and so unique. 



MORE fish parasites are given in this illustration, many of them possessing the most 

 bizarre and unexpected forms. As our space is rapidly diminishing, these creatures 

 must be very slightly treated. 



