Boone, Crustacea, Cruises of "Ara" and "Alva" 205 



ward. The eyes are large, blackish, reniform, set obliquely on 

 strong stalks, the proximal ophthalmic article bears dorsolater- 

 ally on either side distally, a small, rounded, wing-like process. 

 The carapace is two-thirds as wide proximally as long medially, 

 but attains a greater width between the acuminate wing-like pro- 

 duced angles of the lateral margins, which occur about one-third 

 of the carapace length from the posterior margin, while the ante- 

 rior width of the carapace is only slightly more than one-half of 

 the length. The anterior margin is truncate at the base of rostrum 

 and on either side concave, the anterolateral angle being an acute 

 spine. The lateral margins are sinuate, divergent posteriorly, pro- 

 duced to form the downward directed, lateral processes, situated 

 two-thirds of the length from the front; posteriorly the lateral 

 margins converge with the posterior margin, the postlateral angles 

 being rounded. This posterior margin is concave medially. The 

 median carina has the anterior third so faint as to be scarcely a 

 carina, the posterior two-thirds becoming a definite carina, which 

 becomes obsolete posteriorly near the cervical groove. In line with 

 this median carina, there is a small, flat, triangular tubercle on 

 the posterior margin of the carapace. There are two longitudinal 

 sulci, one on either side of the median carina and between each 

 lateral sulcus and the lateral margin, two, well separated, longi- 

 tudinal carinae, the upper of which begins a short distance behind 

 the anterior margin of carapace, is discontinued about 2.5 milli- 

 meters anterior to the cervical sulcus, then resumes ; posterior to 

 this sulcus, the carina is continuous with that bordering the outer 

 postlateral angle and lower lateral margin of carapace. The lower 

 lateral carina originates as an acute lateral spine at the antero- 

 lateral angle of carapace and is unbroken in its slightly sinuate 

 course, terminating near the posterior margin. The cervical 

 groove is sharply defined. Just anterior to it, and adjacent to 

 the longitudinal sulci on the lower side, there is a pair of node- 

 like elevations. 



The third thoracic segment is short, with the anterolateral 

 process produced to an acute tooth or spine anteriorly and 

 rounded unequally posteriorly; above this lateral process, the 

 posterior portion of this segment is separately produced into an 

 elevated, subacuminate process, margined by a carina, which 

 curves upward along the hind margin and is continuous with 

 the curved longitudinal upper lateral carina of this segment. 



