MONOGRAPH OF THE EXISTING CBINOIDS. 625 



white pigment on the thorax, alternating with brown lines. On the abdomen there 

 was a median white line with a brown line on either side, most of the median space 

 being colorless, and a nonpigmented eye being found on each pleuron. The male 

 showed six lines of brownish-purple pigment on the thorax, the remaining portions 

 being colorless save for some dashes of white pigment. In this case the two 

 partners differed slightly; the female showed well- developed white pigment, and 

 the other pigment was brown; in the male white pigment was almost absent and 

 the pattern was formed by a purple-brown darker than in the female. 



Distribution. Albany Island; Albany Passage; Warrior Reef; reefs north 

 of Mabuiag Island; Prince of Wales Channel; Thursday Island; between Cape 

 York and the Aru Islands ; Torres Strait ; Singapore ; Ceylon. 



Depth. Littoral, and down to 9 fathoms. 



SYNALPHEUS STIMPSONTI VAK. MALDIVENSIS COUTIERE. 



This form was found on a crinoid which resembled it in color ; it was taken at 

 Hulule, Male Atoll, Maldive Islands. 



STNALPHEUS CARINATTJS VAR. BINONGCENSIS DE MAN. 



One specimen, a female, is the only known example of this form. It was 

 found on a comatulid dredged by the Siboga in 55 meters at the anchorage off 

 Pasir Pandjang, on the west coast of Binongka. 



SYNALPHEUS BRUCEI POTTS. 



Lieutenant Potts' account of this species is as follows : 



Comanthus annulatus, with which Synalpheus brucei is usually associated, is 

 very variable in color. It will be sufficient here to say that the coloration varies 

 from a light green mingled with yellow and white to the darkest green or even 

 black. The commensal alpheid is generally black to brownish purple in ground 

 color, but the pigmented dorsum is traversed by longitudinal stripes which are 

 free from pigment. Of these one runs down the middle line from head to tail, 

 there are either two or three on each side of the carapace, and two on the upper 

 surface of the chela. In addition, each abdominal pleuron is traversed by a short 

 oblique pigment-free stripe which may by the encroachment of the pigment become 

 a spot. The relative extent of pigmented and nonpigmented areas is exceedingly 

 variable, and corresponds roughly to the depth of coloration of the host which 

 the alpheid inhabits. Individuals which lodge upon a light green comatulid have 

 only narrow red or purple lines of pigment, the remaining portions being unpig- 

 mented ; in those which are associated with a dark green or black host the pigment 

 may be extended over the whole of the dorsum. 



In the vast majority of cases a pair, male and female, of alpheids is found on 

 each comatulid. In a few cases there appeared to be only a single lodger, but then 

 its small size seemed to show that it was too young to have acquired a mate. 



In most cases the pair are similarly colored ; rarely, however, there is a differ- 

 ence, and Potts found one case in which one member was marked with very definite 



