COPEPODS OF THE WOODS HOLE BEGION 



41 



Remarks. — In specimens obtained with a townet the large plumes 

 on the caudal rami are always damaged and often entirely broken 

 away. But even in this condition the copepod can be recognized by 

 the peculiar position of the rami, and by the long bristles on the first 

 antennae. It is a tropical species and was taken in considerable 

 numbers by the present author at Montego Bay, Jamaica, in the 

 summer of 1910. 



CALOCALANUS PLUMULOSUS (Glaus) 

 FlGtTBB 23 



Calanus plumulosus Claus, Die frei lebenden Copepoden, p. 174, pi. 26, figs. 15, 



16, 1863. 

 Calocalanus plumulosus Giesbeecht and Schmeil, Das Tierreich, Lief. 6, Cope- 



poda, p. 26, 1898. 



Occurrence.— Sexersil females were taken by Wheeler at the sur- 

 face in the Gulf Stream south of Marthas Vineyard. 



Distribution. — M e s s i n a (Claus) ; Mediterranean, 

 tropical Atlantic and Pacific (Giesbrecht) ; Gulf 

 Stream (Wheeler) ; Adriatic (Graeffe, Pesta). 



Color. — Female transparent, with orange and red pig- 

 ment scattered irregularly through the body, especially 

 in the head, the fourth and fifth thoracic segments, and 

 the genital segment, and along the sides of the thorax 

 and abdomen. The two large plumes on the basal seg- 

 ments of the first antennae are dark brownish orange ; 

 the plumes on the caudal rami, including the enor- 

 mously elongated one on the left ramus, are light red- 

 dish orange. 



Female. — Segmentation indistinct; genital segment 

 cuboidal; the left caudal ramus with an extra inner 

 plume twice the width and five times the length of the entire body. 

 Terminal endopod segment of third legs with two groups, of fourth 

 legs with one group of spines; fifth legs much longer than in the 

 preceding species, each 4-segmented, end segment tipped with a single 

 long plumose seta and three spines, both margins and the inner mar- 

 gin of the preceding segment heavily fringed with long hairs. Total 

 length, 0.9-1.25 mm. 



Male. — Unknown. 



Remarks. — If specimens are obtained uninjured, the enormous 

 plume on the left caudal ramus will at once identify the species. 

 If this is broken off, the fifth legs furnish the best diagnostic char- 

 acters. The antennae are considerably shorter than in pavo, and 

 each has a single plume on the anterior margin of the basal segment. 

 The caudal rami are much less divergent, and in preserved speci- 



FIGCRE 23. 



Calocalanus 

 plumulosus: 

 Female, fifth 

 legs 



