148 Papers from the Marine Biological Laboratory at Torttigas. 



mottled green and white, with green spines as the prevailing color. Some 

 young specimens show on the green and white groundwork purple pri- 

 mary tubercles and purplish spines. A peculiar color-pattern was observed 

 as a relatively rare variation in the fact that in the interambulacral 

 areas of some specimens the green followed a zigzag pattern on a white 

 ground and extended thus from the apical disk adorally, but in no case 

 observed extended further than the ambitus. The zigzag green color- 

 pattern on a cream-white ground of a specimen measuring 45 mm. in diam- 

 eter is shown in fig. 8. The lower figure on the same plate is of a somewhat 

 larger specimen, measuring 48 mm. in diameter, in which the zigzag pattern 

 occurs only near the apical portion of the test. Both of these specimens 

 with others figured in this paper are now in the collections of the Museum 

 of Comparative Zoology, at Cambridge, Mass. This type of color-pattern 

 was quite new to Dr. Clark and Professor Tennent, both of whom had 

 worked on the species, and I had never seen it before, although I have 

 studied many specimens from different localities. 



Being busy with other species, no attempt was made to collect a large 

 series of Toxopneustes variegatus for a study of ocular plates, but 400 speci- 

 mens are tabulated. These are of various sizes, but none were young and 

 they were not graded into sizes for comparison. Of this series, 2 specimens, 

 0.5 per cent, have ocular I only insert as arrested variants, and one specimen, 

 0.3 per cent, has ocular V only insert; 84 per cent have oculars I, V insert 

 (figs. 8, 9), which is the species character in all localities; 15 per cent are pro- 

 gressive variants with oculars I, V, IV insert. Four specimens, i per cent, 

 are aberrant variants and all of these have oculars I, V, II insert. The 

 ocular character is practically the same as I showed previously in this species 

 from several localities, but the Montego Bay material has a somewhat lower 

 percentage of I, V and corresponding higher percentage of I, V, IV insert. 

 My previous observations on i ,043 specimens gave 90 per cent I , V insert 

 and 8 per cent I, V, IV. Comparison of the tabulation of this species may 

 be made with that of the closely allied Toxopneustes atlanticus (A. Agassiz) 

 from Bermuda, in which I showed (Phylogeny of the Echini, p. 161) that 

 the mature series (45-77 mm. diameter) has a much higher percentage (28 

 to 29 per cent) of oculars I, V, IV insert than has Toxopneustes variegatus. 

 The Montego Bay experience in the cases of several species brought out the 

 fact clearly that for a close study of variation it is very desirable to tabulate 

 ocular plate characters in specimens from a single definite locality because 

 considerable difference in a given species may occur in different localities. 



In Toxopneustes variegatus, when opened fresh, it is found that the proxi- 

 mal part of the testh extend horizontally over the top of the lantern and the 

 teeth are bent back on themselves in the same plane, also the dental capsules 

 which inclose the base of the teeth are large and bladder-like, in these char- 

 acters differing from Eucidaris and Centrechinus , but agreeing with Strongy- 

 locentrotiis as I previously described it. In a young specimen 12 mm. in 

 diameter, the auricles are still separate, but in larger specimens they are 



