480 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxviij. 



chilensis, from Lota, Chile, and Homoiotes palliata, the t}^pe of a new 

 genus, locality unknown. 



In addition to these seventeen new species the present paper gives 

 for the first time the development stages of two species, Oaligus rapax 

 and O. curt us; almost the entire anatomy of a third, EchePus typicus 

 Kroyer, while it corrects or largely supplements the anatomical 

 details and rectifies the systematic position of seven other species, 

 Oaligus pet larny dis Kroyer, C. prod 'act its Dana, C. thymni Dana, Lepe- 

 ophtheirus thompsoni Baird, L. sahnonis Kroyer, L. pacificus Gissler, 

 and Oaligus centrodontl Baird, the last a non-American species. 



Here also are presented for the first time a. comparative anatomy of 

 the different species of Oaligus and Zepeophtheirus, and artificial keys 

 for the determination of all known species under the several genera. 

 In the development are given for the first time figures of a metanau- 

 plius and the details of its anatomy. And there is introduced the first 

 continuous life history of any species belonging to the family, together 

 with a comparison of the life histories of several species and at least 

 two genera. 



This subfamily, the Caligina?, is particularly interesting because the 

 genus Oaligus, which is the type of the entire family, is one of the 

 oldest among the parasitic copepods and formerly included many 

 species which are now referred to other genera. Among these were 

 some which resembled the true Oaligus very closely, except that they 

 lacked the lunules or sucking disks on the frontal plates. From these 

 Van Nordmann created the genus Zepeophtheirus in 1832, but it was 

 not generally accepted at first, and the species of both genera continued 

 to be included under Oaligus by many authors up to the appearance of 

 Kroyer' s excellent memoir in 1863. 



The genus Anuretes also was first placed by Kollar under Oaligus 

 in the collection of the Vienna Museum. Like Zepeophtheirus it lacks 

 the lunules on the frontal plates, and hence Kroyer, who was the first 

 to publish a description of the species, classified it as a Zepeophtheirus, 

 and it was not until 1865 that it was established as a distinct genus by 

 Heller. 



Of the other two genera, one, Oaligodes, is simply a Oaligus with 

 the free segment elongated into a neck and the genital segment and 

 abdomen modified slightly, while the appendages are identical in the 

 two. The other genus is the new one Homoiotes, and differs only in 

 having the genital segment covered with a dorsal plate. It has not 

 thus far been found in North American waters, but there is every 

 probability that it will be at some future time. 



These genera are very closely related to one another therefore, and 

 since both the males and females of all except Caligodes can swim about 

 freely they furnish an excellent group to contrast with the Argulidse 

 on the one side and the Pandarinte on the other. The Argulidse are 



