Bibliographical Notice. 481 



talus, Steens., with. Caligus. There are several interesting observations 

 on the development of Caligini. At first the young larvae have 

 only two pairs of appendages ; but after changing skin their form 

 becomes more elongated, and they acquire a third pair; they 

 go, probably, through a further series of transformations before 

 fixing themselves, but these are at present unknown. Of several 

 species the Chalimi or fixed larvae have been observed — those of 

 Lepeophtheirus Hippoglossi through three different stages. In the 

 first stage (length f") the genital joint showed two pairs of appen- 

 dages, or perhaps one double-oared pair ; in the second stage (length 

 1-j'") these appendages had disappeared, the genital joint and the 

 tail were still shorter in proportion to the fore part of the body, the 

 "fork" was not yet visible ; nor could this be observed in those belong- 

 ing to the third stage (length 2"'). As, however, the smallest adult 

 females are 5'" long, several transformations are still to be observed. 

 Dr. Kroyer' s observations on the Chalimi of Caligus curtus, C. 

 Gurnardi, and Trebius caudatus were quite analogous. Of C. Chei- 

 lodactyli larvae were observed very nearly of the same size as the 

 adults. Neither of the "fork" nor of the generative organs was the 

 least vestige distinguishable ; but the sucking-cups had begun to 

 form themselves. The organ of fixation, which does not grow in pro- 

 portion with the larva, and of which the place is discernible in all 

 adult Caligi just behind the frontal emargination, shows rather a 

 complicated structure, and distinct variations in different species, so 

 that these may be recognized by it. The young of Lee margins muri- 

 catus and Cecrops Latreilli, which have been observed shortly after 

 assuming the adult form, show some remarkable differences, particu- 

 larly in the fact that the same piece which in adult Caligini is described 

 as the frontal piece presents itself here as a distinct ocular seg- 

 ment or joint, which afterwards disappears, principally owing to 

 the growth of the second pair of antennae : it exhibits two rather 

 large eyes, which of course disappear with it. To this ocular seg- 

 ment the remains of the organ of fixation were attached, proving 

 that this segment corresponds to the frontal piece of an adult 

 Caligus, though this never carries eyes. In the structure of the adult 

 Caligini certain diminutive spines on the concave side of the second 

 hook-shaped antennae, as well as on the hooks of the second pair of 

 feet, and which are in connexion with extensive glandular(poisonous ?) 

 apparatus, may be particularly mentioned. The glands which feed 

 the hooks of the second pair of feet are situated close under the 

 dorsal shield, and are particularly easily distinguished in Lcemargus, 

 where they have a milky colour, and shine through the shield. 

 Their structure is convoluted ; and Dr. Kroyer has followed their 

 ductus, which forms a larger reservoir in the claw itself, to their 

 termination in a very diminutive spine on the concave side of the 

 hook. Dr. Kroyer also recommends Lcemargus muricatus for ob- 

 serving the copulation. As is well known, the males remain attached 

 to the female even after death, by means of their hooked antennae 

 and feet ; nor would a less secure adhesion suffice, for the work of 

 protruding the spermatophores, and fixiug them, one to each of the 



