294 Ortmann — Linuparus atavus. 



Specimen (a) shows beautifully the frontal margin, the seg- 

 ment of the antennulse, the stalks of the antennae and parts of 

 the flagella, the basal joints of the antennulse, the epistoma, 

 and the hinder part of the abdomen. The upper surface of 

 the carapace is much crushed, and the place of the sternum is 

 occupied by a large hole. Of the abdomen, the four last 

 abdominal segments and the telson are present ; of the first and 

 second segments only a few pieces are recognizable. In speci- 

 men (b) the upper surface of the carapace is nearly complete, 

 there is only a hole occupying the gastrical region and a few 

 smaller ones ; the frontal horns are better than in the first 

 specimen. The anterior part of the abdomen and the sternum 

 are complete in specimen (&), but the anterior part of the body 

 (beyond the frontal margin) is imbedded in the matrix, and the 

 posterior part of the abdomen is wholly absent. Parts of the max- 

 illipeds, pereiopods, and pleopods are visible in both specimens. 



Description. — Carapace nearly rectangular in outline. 

 Frontal margin truncate, nearly straight, connected with the 

 segment of the antennulse on both sides of the eyes. Frontal 

 horns approaching each other, compressed, but diverging from 

 the bases outward, their anterior margin with a few small teeth, 

 no median rostral spine being visible. Antero-lateral angles 

 formed by spines. Cervical groove distinct. Anterior part of 

 carapace (in front of the cervical groove) with two spines just 

 behind the frontal horns, which are a little more distant from 

 each other than the latter, and with three tubercles forming a 

 triangle. A curved, longitudinal series of three spines between 

 the median line and the lateral margins. Hinder part of cara- 

 pace tricarinate, each keel bearing a number of small spines. 

 Otherwise the surface of the carapace is only granulate and 

 punctate. (The arrangement of the spines on the anterior 

 part is very like to that of the living Linuparus !) 



Abdominal segments in the median line provided with short, 

 conical spines. (Similar spines are found in Linuparus tri- 

 gonus on the anterior segments, but are wholly wanting in all 

 other genera of Palinuridse, except in one species of Paerulus : 

 here, however, they are of a different character !) The first 

 segment has only one spine, the second has two simple spines, 

 on the third segment the posterior one is provided, in specimen 

 (a) with one, in specimen (b) with two additional tubercles, 

 one behind the other. The fourth segment has two double- 

 spined tubercles; the tips of the spines are placed one behind 

 the other. The fifth segment has two simple spiniform 

 tubercles. On the sixth segment, however, are two low double 

 spines, placed side by side each near the' median line, and on 

 the posterior margin are two small spines placed close to the 

 median line. The segments from the second to the fifth have 

 each two sharp tubercles on each lateral part ; the sixth has 

 only one. The epimera are spined on the margins, bat the 



