400 PERCY SLADEN TRUST EXPEDITION 



6. Thalassocaris affinis Borradaile, 1915 (Plate 58, fig. 4). 

 Ann. Mag. Nat. Hist. (8), xv. p. 208. 



Diagnosis: The species is closely related to T. lucidus (Dana), 1852, but differs 

 from it in the following points : the rostrum is less strongly upcurved, and is usually 

 rather shorter. Its formula is ^E^. The "teeth" on the antennal scale are hooked 

 thorns, stronger than in T. lucidus and set wider apart. The hands of the second legs 

 are of the shape of T. crinitus — rectangular, with widely gaping fingers and a strong 

 basal knob on the fixed finger, and a stout tooth on the moveable finger. The merus 

 in the ivalking legs bears the stout thorns present in T. crinitus but neither mentioned 

 nor figured by Dana for T. lucidus. 



Length of the longest specimen 25 mm. 



Many of the specimens are mature, and some of them are considerably larger than 

 the smaller specimens of T. crinitus. T. affinis appears to be intermediate between 

 T. lucidus a.-ndi T. crinitus. It was takeij at various depths down to 26 fathoms in the 

 Maldives and at Saya de Malha. 



7. Thalassocaris maldivensis Borradaile, 1915 (Plate 58, fig. 5). 

 Ann. Mag. Nat. Hist. (8), xv. p. 208. 



Diagnosis : The body is stout and compressed. The rostrum outreaches the antennal 

 scale, at first descends and then is horizontal, and has the formula ^, two of the dorsal 

 teeth standing behind the orbit with sometimes a vestigial tooth behind the first of 

 them. Suborbital and antennal, but no supraorbital or hepatic spines are present. 

 The antennal stalk is slightly outreached by the antennular, and extends to about one- 

 third of the length of the antennal scale, which is without teeth on the outer edge. 

 The third maxilliped nearly reaches the end of the antennal scale. The Jirst leg ends 

 at the middle of the last joint of the third maxilliped. The second leg outreaches the 

 third maxilliped and has a small chela of simple form, the wrist about as long as the 

 arm, and the fingers shorter than the palm. The legs of the last three pairs are sparsely 

 hairy and of moderate length and stoutness. The abdominal pleura are sharp pointed. 

 The third abdominal somite has no spine on its hinder edge. The telson is longer 

 than the uropods and has four pairs of dorsal spines and two fixed terminal spines. 



Length of the longest specimen 19 mm. 



Peculiar features of the species are the absence of the spine on the third abdominal 

 segment and of the supraorbital spines, and the feebleness of the second leg. The first 

 maxilliped differs greatly from that figured by Dana for T. lucidus, but the latter was 

 probably drawn from a damaged specimen. 



Specimens were taken in Suvadiva, Mulaku, Haddumati, and S. Nilandu Atolls in 

 the Maldives. 



Superfamily Pal^emonoida. 



Family Alpheid^. 



The Alpheid Prawns collected by Professor Gardiner's Western Indian Ocean 

 Expedition form the subject of a separate report by Prof Coutiere in this volume. 



