578 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxvm. 



CALIGUS CURTUS Muller. 

 Plate X, figs. 8, 24, 28 in the text. 



Caligus curtus Muller, 1785, p. 130, pi. xxi, fig. 1. — Smith, 1874, p. 575. — Rath- 

 bun, 1884, p. 486. 



Caligus mulleri Leach, 1816, p. 405, pi. xx, figs. 1-8. — Dana, 1854, p. 1352. 



Caligus bicuspidatus Nordmann, 1832, II, p. 17. 



Caligus americanus Pickering and Dana, 1838, p. 65, pis. in, iv, v. — Dana, 

 1854, pi. xcni. 



Caligus diaphanus Baird, 1850, p. 269, pi. xxxii, fig. 1. 



Caligus elegans van Beneden, 1851, p. 91, a male. 



Female. — Carapace somewhat longer than the rest of the body, obo- 

 vate. Frontal plates distinct, the anterior margin well rounded and 

 incised at the center. Lunules large and circular, not very widely 

 separated and not projecting. Posterior sinuses narrow, shallow, and 

 with nearly parallel sides; the median lobe less than half the entire 

 width, projecting for two-thirds of its length beyond the lateral lobes; 

 the latter broad and well rounded (fig. 113). 



Thoracic area quadrilateral, comprising about one-third of the cara- 

 pace; its anterior groove nearly straight. Eyes small and situated far 

 forward. Free segment short and very narrow, not more than half 

 the width of the genital segment, and spindle-shaped. Genital seg- 

 ment oblong, half as long as the carapace, with parallel sides and well- 

 rounded corners. There are no lobes on this segment and the fifth 

 legs are not visible dorsally. Abdomen short, half as long as the 

 genital segment, often slightly swollen at the center. Anal laminae 

 rather small with very long setae; egg strings wide and about as long 

 as the entire body. 



Anterior antennae large, the basal joint much longer and wider than 

 the terminal and both joints plentifully supplied with setae and spines. 

 These antennae stand out very prominently from the carapace. Second 

 antennae stout, with a long accessor} 7 spine on the inner border of the 

 terminal claw, near its base. 



First maxillae of good size and situated close to the edge of the 

 carapace, the terminal portion strongly curved and the base consider- 

 ably swollen. Second maxillae broadly triangular with curved sides, 

 abruptly narrowed near the tip into an acuminate spine. This repre- 

 sents the endopod of the appendage, while upon the ventral surface of 

 the base of the triangle is the rudimentary exopod, consisting of a long, 

 slender spine and three or four small setae. This exopod is articulated 

 with the base of the endopod and is capable of considerable motion. 



The mandibles are curved inward and dentated along the inner edge, 

 the number of teeth being about fourteen. 



First maxillipeds very slender and weak, the terminal joint much 

 longer and narrower than the basal, with a short spine on its inner 

 margin near the distal end. The two cluws at the tip of these append- 



