no. 1404. PARASITIC COPEPODS— CALIGIDJS— WILSON. 481 



practically nondegenerate, while the Pandarinse are very evidently 

 degenerate; this group therefore forms a connecting link between 

 the two and enables us to discover and emphasize the initiatory steps 

 in degeneration. 



They thus possess the greatest possible ecological interest, and a care- 

 ful study of their habits and mode of life can not fail to yield valuable 

 facts and suggestions. 



HISTORICAL. 



The first accounts that can be referred to these genera with any 

 degree of certainty are those of Gunner (1765), Stroem (1762), and 

 Raster (1765). The}- describe and figure some parasites which they 

 call fish lice, but evidently they entirely mistook the nature of the ani- 

 mals, since they regarded the egg strings as antenna? and printed their 

 figures upside down. 



But the figures were accurate enough to show that these were really 

 parasitic copepods belonging to the family under discussion. Muller 

 in 1776 showed that these "antenna?" were egg strings, and he also 

 found and described the true antenna 1 . But he blundered in regard 

 to the eyes as badly as his predecessors had done in regard to the anten- 

 na 1 , mistaking for them the sucking disks on the frontal plates and fail- 

 ing entirely to find the true eyes. Hence he introduced his specimens 

 under the genus name JBinoculus, a name which survived for many 

 years. Slabber (1778) described and pictured one of the Caligina? 

 under the name Oniscus lutosus; he also delineated the antenna? and 

 many of the other appendages correctly and his figure is right side up. 

 Muller in a second paper (1785) corrected his previous error by dis- 

 covering that the sucking disks were not eyes. He then realized that 

 these copepods could no longer be classed in the heterogeneous group 

 known as Buioculus, and accordingly founded for them the genus 



( 'ill H J II X. 



But again he blundered, for the very name" tells us that he did not 

 find the true eves, but considered these parasites to be blind. 



Stroem (1762) was the first to study the habits of the genera from 

 living specimens, and he has given us many interesting observations. 

 A few additional data have been given by Leach (1813-11), Lamarck 

 (1818), Johnston (1824), Desmarest (1825), Burmeister (1833), Rathke 

 (1843), Baird (1850), Kroyer (1863), Heller (1865), Claus (1875), 

 Hesse (1877, L883), and T. Scott (1894, 1900). 



But although this list of names looks quite formidable they have 

 really given us almost nothing upon the habits and development of 

 the group. Johnston established for the first time the external differ- 

 ences in the sexes of Caligus by describing in detail a male and a 

 female of Caligus curtus from the cod. 



" ( aliijus, from caligo, a medical term fur blindness or weakness of the eyes. 



