218 CEYLON PEARL OYSTER REPORT. 



Petrolisthes (?) armatus (GiBBEs). (See HENDERSON, 7.) 



One damaged specimen, from Galle lagoon, is doubtfully referred to this species. 



Length of carapace, 4 millims. ; the carpus of both chelipeds is armed with 3 

 spines ; ambulatory legs missing. P. armatus is a West Indian species, and so would 

 be a new record for Ceylon. 



Petrolisthes serratus, HENDERSON (7). 



Locality : Coral reef, Galle ; one female bearing eggs. Length of carapace 

 2 centims. This is a new record for Ceylon. 



Porcellana serratifrons, STIMPSON. (See HENDERSON, 7.) 

 Localities : (1) Pearl banks, Gulf of Manaar, shallow water, five young specimens ; 



(2) south end of Cheval Paar, Station XLIX., 9 to 13 fathoms, one specimen; 



(3) south of Galle, deep water, Station XLL, 100 fathoms, two specimens ; (4) Galle 

 coral lagoon, shallow water, one specimen. Carapace of largest measured 8 millims. 

 This is a new record for Ceylon. 



Porcellana quadrilobata, MIERS (12). 



Localities : (1) Welligam Bay, Station XXXIV., 2 to 7 fathoms, one specimen ; 

 (2) Gulf of Manaar, outside pearl banks, Station LXIIL, about 40 fathoms, one 

 specimen; (3) off Mount Lavinia, Station XL VI., 25 to 30 fathoms, two specimens; 

 the carapace of largest measured 5 millims. This is a new record for the Indian 

 Ocean, as the species has only been found on the coast of Queensland. 



Porcellana hornelli, n. sp. Text-fig. 1. 



Carapace oval in outline, naked, very convex, a little longer than broad,* and 

 obscurely lineolate ; front fairly prominent and four-lobed. The two median lobes- 

 one on each side of the centre have rounded apices which are minutely notched and 

 are slightly longer and much broader than the two lateral lobes, each of which is 

 triangular, curved, and terminates in a spine. 



Eyes small, and protruding but little. 



Lateral margin of carapace armed with a series of spines. There is a large spine 

 behind the orbit ; and very near to it, but still nearer to the eye, is a much smaller 

 one. A little further back are two additional spines, and between them is a rounded 

 lobe bearing a few minute spines. 



The external maxillipeds have the ischium a little shorter and broader than the 

 merus. Both these joints are flattened from above, and each has its internal face 

 produced into a rounded lobe. 



Chelipeds smooth, obscurely lineolate, and a little longer than the carapace. The 

 merus has its inner border produced into a rounded crest obscurely toothed. Carpus 



* In the figure (p. 219) the carapace is shown rather too narrow. 



