692 



FEOCEEDTNG.S OF THE NATIONAL MUSEUM. 



In the latter case these appendages are veiT rudimentary, to be sure, 

 but the,y are all the copepod ever possesses and are as full}^ developed 

 as in the adult. 



Of the other appendages in this Ahhioii chalimus the first antennae 

 are normal and two-jointed, l>ut the basal joint is nearly concealed 

 in a dorsal view by the projecting- margins of the frontal plates. 

 Both joints are plentifully supplied with normal setfe, the long and 

 dichotomously branched forms of the metanauplius having entirely 

 disappeared. 



The second antennje (fig. 11) are like those of the previous stage 



and continue to serve as organs 

 of attachment by which the larva 

 is fastened to its host. This con- 

 stitutes the most important dif- 

 ference in the development of 

 the two subfamilies. 



In all the genera belonging to 

 the Caliginai whose larvse have 

 thus far been obtained, the chali- 

 mus and subsequent stages up to 

 the adult form are characterized 

 by the presence of a frontal fila- 

 ment, by means of which the larva 

 is securely fastened. 



The remains of this filament 

 may be seen in the A^oung adults 

 of both sexes and of all the 

 genera, and is satisfactory proof 

 of its presence during develop- 

 ment even in those forms whose 

 larva3 have never been actualh' 

 seen. 

 In the genus Alehlon^ on the contrary, there is no frontal filament 

 at an}'^ period of development, the second antennae serving as the onh' 

 organs of attachment up to the adult stage. 



The life historv of Alehlon is the only one at present fully known 

 in the subfamih' Euryphorinte, but we have the same evidence here in 

 a negative way that we had positively in the Caligina?. None of the 

 adults in an}' of the genera thus far examined show traces of a frontal 

 filament; the 3'ounger adults certainly ought to do so, provided such 

 a filament exists during their development. 



The first maxilhB are minute and easily overlooked; the}^ are quite 

 close to the margin of the carapace, and have the shape of a comma, 

 the base nearly spherical while the tip is short and l)lunt. 



V 



Fig. 11.— The second antenna and first .max 



ILLA OF THF.C HALIMUS OF ALEBION GLABER. 



