386 CEYLON PEARL OYSTER REPORT. 



Upper Margin of the Orbit behind the Supra-ocular Spine. All have 3'3, of which 

 the third is the largest. 



Hepatic Margin. All have 3*3. 



Branchial Margin. Fifteen specimens have 5"5 ; one has 4*5 ; one has 5 - 6 ; one has 

 57 ; one has 6*6 ; one has 67. 



B. Specimen (a), an ovigerous female, differs from the other examples in the 

 collection in various ways, as set forth below, and goes with Herbst's " type "-specimen 

 of the species : 



(1) The rostral spines are more strongly curved outwards at their tips (see Herbst's 

 figure). 



(2) The hepatic regions are not so much pinched in dorsally. 



(3) The under surface of the basal antennal segment is smooth and its antero-lateral 

 angle is produced into a longer, more definite spine, the border of which is entire (in 

 the A -specimens the outer half of the under surface of the basal antennal segment is 

 more or less granular, and its antero-lateral angle is produced to form a triangular 

 and less spiniform infra-orbital projection with a crenulate border). 



(4) The arrangement of spines is different. 



Dorsal surface of the supra-ocular hood of either side has a definite blunt spine. 

 The anterior and posterior angles of the eave form blunt projections. 



Dorsal surface of branchial region of each side has three arranged in a longitudinal 

 row ; of each row the two anterior members are spinules merely, the posterior one is a 

 well-developed spine. There is also a denticle on the branchial region which would 

 lie about one-third way along a line drawn from the large spine just named to the 

 middle point of the gastro-cardiac groove. 



Gastric Region. Two not very obvious median tubercles. 



Upper margin of orbit behind the supra-ocular eave of either side has three spines, 

 the middle one much the strongest. 



Hepatic Margin, 0. 



Branchial Margin, 7 8 (on the left side the anterior four are granules, the three 

 posterior are larger ; on the right side the anterior five and the seventh* are granules ; 

 the sixth and eighth are larger). 



Posterior Border of Carapace. A pair of spines close together, one on either side 

 of middle point. 



Of the above particulars the form of the rostral lobes, the strong development of 

 the middle one of the three supra-orbital spines, the presence of the two spines of the 

 posterior border, and the crenulate margin of the antero-lateral spiniform production 

 of the basal antennal segment, are conveniently conspicuous characters. 



Micippa margaritifera, Hendekson, 1893 Al, p. 253 ; A.Invest., pi. xxxv., fig. 3. 

 Localities : Jokkenpiddi Paar, two specimens (ovigerous ? ) ; Aripu coral reef, one 



