JIACRUKOl'S DECAPODA OF THE SUDANESE RED SEA. 



307 



of the first pair ot'legs in (lie male only, the female having the first pair of. 

 legs simple. In this character the species are distinct. These two species 

 also agree in the character of the dactyli of the third and fourth pairs of 

 legs. U. pseudochelata differs from U. heterocJieir in the following points : — 

 (i.) the much shorter rostrum and the almost complete absence of lateral 

 teeth ; (ii.) the presence of tubercles on the rostrum ; (iii.) the relatively 

 longer flagella to the antennnle ; (iv.) the absence of spines and teeth on 

 the limbs and other appendages; (v.) the different form of the pseudochelate 

 limb and the fact that it is common to both sexes; (vi.) size. 



In general facies and structure the two species are closely allied, but the 

 differences already mentioned raav be considered of specific value. 



Fig-. 1. 

 9 



10. 

 11. 

 12. 

 13. 



14. 

 15. 

 16. 



17. 



EXPLANATION OF THE PLATES. 

 Plate 27. 



Pseudosqiiilla mcgalvphthahna, Bigelow 



Anehistus inermis (Miers). 

 Gtmodnctylus brevisqttamatus, Paulson 



7. Penceopsis stebbinyi (Nnbili). 



8. 



Periclimenes calmani, n. sp. 

 Puna-opsis millanti (Nobili). 

 Athanas crosslandi, n. sp. 



Dorsal view of anterior region. 

 Lateral view of eye to show the real 

 proportion between cornea and 

 peduncle. 

 Dorsal view of sixth abdominal seg- 

 ment and telsjn. 

 Chela of leg of the first pair of the male. 

 Dorsal i iew of anterior region of 



specimen 28 mm. 

 Dorsal view of sixth abdominal seg- 

 ment and telson of the same specimen. 

 Carapace and rostrum. 

 Merus of last thoracic leg of a male to show 



notch. 

 Thelyeum. 

 Petasma. 



Lateral view of anterior end. 

 Thelycum. 



Lateral view of anterior end to show the 

 relations of the rostrum, extra- and iufra- 

 corneal spines, and eyes. 

 Autennular peduncle. 

 Antenusl peduncle and scale. 

 Leg of the first pair. 

 Leg of the third pair. 



Fig. 1. Synalpheus quinqucdens, n. sp. 

 2. 



3. ,j ii 



J. 



Plate 28. 



Dorsal view of anterior end. 



Large chela. 



Leg of the second pair. 



Leg of third pair. 



