ISOPODA OF THE 'LIGHTNING' AND OTHER EXPEDITIONS. 131 



2. Paeanthuka tenuis, G. O. Sars. (Plate XXVII. fig. 1.) 

 1872. Paranthiira tenuis, G. O. Sars, Bidrag til Kundskabcu om Dyrelivet paa vore Havbanken, 

 Vidensk. Selsk. Porhandl. 1872, p. 89. 



Head with the sides scarcely convex, almost parallel. Perseon with three first 

 segments strongly keeled below; back of all the segments perfectly smooth ; second 

 segment contracted as usual behind, but only slightly so ; last two thirds the length of 

 the penultimate. Pleon (i. pi. d) well developed, and its segmentation distinct, as 

 long as the penultimate segment of peraeon. 



Antennae (i. a.s & i. a.i) short and thick, not longer than the head ; peduncles of 

 both pairs stout and strong, and their flagella very minute, about equal in length to the 

 last joint of peduncle. 



First gnathopods (i. gn^) stout and strong ; basos very thick, not twice as long as 

 broad ; ischium slightly longer ; meros produced anteriorly as usual to form a cup for 

 the reception of the base of the hand, the bottom of the cup free from any appearance 

 of angularity ; wrist very minute ; hand subtriangular, palm furnished with a small, 

 tubercular, thumb-like projection at the proximal angle, and is margined with spines ; 

 finger strong, curved, equal in length to the palm. The hinder pairs of peraeopods 

 (i. prp*) have the basos subequal to the ischium, neither of these joints being more 

 than three times as long as broad ; meros subtriangular, rather more than half as long 

 as ischium ; wrist triangular, minute, so small that the hand and meros meet 

 behind it ; hand long-ovate, three to four times as long as broad, anteriorly furnished 

 with three equal spines ; these spines have a cilium springing from their side, and there 

 is a similar cilium-furnished spine on the wrist ; finger curved, as long as the hand. 



Telson (i. pi. d) broadly spear-shaped. Uropods with the outer and upper branch 

 short, but very wide, so that combined they form a complete dome overhanging the 

 telson ; inner branch long, narrow-lanceolate, projecting considerably beyond the telson, 

 terminating in a bunch of long setae. 



Length ]4 millim. 



One specimen from the ' Porcupine ' Expedition, 1870 (Station 22, off Lisbon, lat. 

 38° 15' N., long. 9° 33' W., in 718 fathoms). 



Professor G. O. Sars has kindly sent us one of his type specimens, taken in 150-200 

 fathoms off the Island of Hvitingsoe, near Bergen, in Norway. This specimen, which 

 is very small (6 millim.) closely agrees with the ' Porcupine ' example, except that the 

 thumb-like tubercular process of the palm of the hand is more developed. 



Genus 6. Calathuka. 



Calathuea beachuta (Stimpson). (Plate XXVI. fig. i.) 

 1854. Anthura brachiata, Stimpson, Marine Invertebrata Grand Manan, p. 43 ; 1873. S. I. Smith, 

 United States Ksh and Fisheries Report (Invertebrate Animals of Vineyard Soimd), p. 573. 



