64 CRUSTACEA MALACOSTRACA. II. 



to contain a large quantity of calcium, as it is firm but yet fragile. The walking legs are inserted 

 in small holes in the firm wall of the segments. 



Remarks. This genus, founded on some specimens of a single species, is the most aberrant 

 type of the family hitherto discovered. The three most interesting features are: the rudimentary an- 

 tennae, the fiision of the last thoracic segment and all abdominal segments in a single portion with 

 feeble furrows indicating the limits between the seven segments, finally the coalescence of all five 

 pairs of long, unjointed pleopods in the subadult male. 



In the number of joints in the antennulas the genus shows affinity to the preceding genera 

 Paratanais and Typhlotanais , while the similarity of second pair of legs with third pair resembles the 

 features in Leptognathia and Crypfocope; the reduced mandibles are somewhat similar to those in 

 Tanaoptis- 



40. Agathotanais Ingolfi n. sp. 

 (PI. VI, figs. 5a- 5 o.) 



Female (without marsupium). Body about six and a half times as long as broad. Cara- 

 pace (fig. 53) about as long as the two following segments combined, somewhat longer than broad, 

 seen from above ovate, with the lateral margins considerably convex to near the front end which is a 

 little less than half as broad as the base of the carapace and considerably less than half as broad 

 as the carapace a little behind the middle; frontal process somewhat short and obtuse. 



Antennulae a little shorter than the carapace, moderately strong (fig. 5c). First joint consider- 

 ably longer than the two other joints combined, about three and a half times as long as deep at the 

 base, with the subdistal part as deep as the middle but a little narrowed between these places; seen 

 from above it is distinctly thickened on the outer side both at the middle and near both ends. Second 

 joint short, about half as long again as deep; third joint twice as long as the second, somewhat robust, 

 with the terminal setse shorter than the joint. Antennse consist of a minute conical joint termin- 

 ating in a few setse. 



Chelipeds (figs. 5b and 5h) slender. Basal joint somewhat longer than deep, without any- 

 posterior protuberance, but attached to the cephalothorax by an oblique articulation, and the distance 

 between this articulation and the front lower angle of second thoracic segment is about as long as 

 the joint. Carpus about twice as long as the basal joint, between three and four times as long as 

 deep, with the lower margin undulate. Chela about as long as the carpus, three times as long as 

 broad; movable finger a little longer than the front margin of the hand; fixed finger near the base 

 considerably broader than the movable, with three low, protruding angles on the distal part of the 

 incisive margin. 



Thoracic segments (fig. 53) decrease in breadth from second to seventh. Third segment slightly 

 longer than the second and slightly shorter than the fourth; fifth and sixth segments each somewhat 

 longer than the others; seventh segment as long as second. Second segment not quite as broad as 

 the carapace; broadest a little behind the anterior margin, tapering rapidly to the front angles and 

 considerably to the posterior margin; third segment nearly as the second but its broadest part a little 

 longer from the front end; fourth segment broadest not much before the middle and tapering to both 



