NO. 5.] ACCOUNT OF THE SPECIES. 123 



them very strong, and issuing from cup-shaped ledges. From the last joint 

 7 or 8 such setae originate, forming together a large brush. 



The posterior antennae (fig. 3) somewhat resemble in structure those in 

 the Calanoida, having both rami well developed. The basal part is compa- 

 ratively small, with its 2 joints imperfectly defined, and carries at the end 

 anteriorly a single ciliated seta. The inner ramus is gently curved, and 

 consists of 2 nearly equal-sized joints, the 1st of which exhibits a distinct 

 ledge somewhat beyond the middle of the anterior edge, carrying 2 unequal 

 setae. The distal joint is somewhat constricted at the base, and very slightly 

 dilated in its outer part, exhibiting traces of the bilobular form characteristic 

 of the Calanoida. The anterior lobule, however, is only indicated by a very 

 slight bulging of the anterior edge, carrying 3 or 4 successive setae increasing 

 in length distally. From the transversely truncated tip, 8 or 9 very slender 

 setae originate very close together, some of them much elongated, con- 

 siderably exceeding in length the whole antenna. All the setae are fringed 

 with stiff hairs, unequal, and rather far apart. The outer ramus is about 

 the length of the proximal joint of the inner, and cylindrical in form, being 

 divided into 7 well-defined joints, the 1st of which is the largest, all the others 

 very short. It carries in all 10 ciliated setae of moderate length, 2 of which 

 issue from the 1st, 3 from the last joint. 



The mandibles (fig. 4) likewise recall somewhat those in the Calanoida, 

 both in the structure of the masticatory part, and in the very full develop- 

 ment of the palp. The masticatory part is rather broad, securiform, and has 

 the cutting edge divided into 8 comparatively small and simple teeth, the 

 outermost of which is the largest, and separated from the others by a deep 

 incision. The palp is considerably larger than the body of the mandible, and 

 is distinctly biramous, with the basal part oblong quadrangular in form, and 

 carrying 3 setae inside, 2 at the end, and one somewhat beyond the middle. 

 Both rami are uniarticulate and lamellar in structure, about equal in size, 

 but of somewhat different shape. The inner ramus is oval in form, and 

 carries along the oblique inner edge a row of 6 remarkably large and coarsely 

 ciliated setae, increasing in length distally. The outer ramus, which issues 

 from the basal part somewhat more proximally, has the form of a triangular 

 lamella, which likewise carries 6 large, ciliated sets. 



