46 



BULLETIN : MUSEUM .OF COMPARATIVE ZOOLOGY. 



Asymmetron orientale, sp. nov. 



Plate 1, Fig. 4. 



Seven specimens of this species were dredged in sixteen fathoms of water at 

 Hanimadu, Tiladummati Atoll. They varied in length from 18 mm. to 9 mm., 

 and their general proportions and structural features suggested at once that 

 they belonged to the species Asymmetron lucayanum Andrews. Although the 

 material on which Andrews based his description came from the Bahamas, 

 Cooper (1903, p. 348) has recently claimed that the same form also occurs in 

 the Maldives. In discussing this question he states that " the only point in 

 which the Maldivan and West Indian forms consistently differ from one another 

 is in their size. The average length of the Maldivan specimens is 23 mm., the 

 extremes being 18 and 30 mm., thus being nearly double the length of the 

 Bahama specimens which Andrews found to average 13 mm. In spite of this 

 difference the average myotome formula for the two forms remains practically 

 the same, the mode in each case being sixty-six myotomes, i. e. forty-four from 

 the head to the atriopore, nine from the atriopore to the anus, and thirteen 

 from the anus to the tail." 



Observations on the seven specimens obtained by Mr. Agassiz confirm most 

 of these statements, as may be seen l)y inspecting Table 3, in which records 

 from three of the seven individuals are given, and below these for comparison 

 average records for the eastern form as given by Cooper (1903, p. 348) and by 

 Punnett (1903, p. 362), and for the western by Andrews (1893, p. 242). It 

 is obvious, as Cooper states, that in all these characters, except size, the eastern 

 individuals agree with the western ones. 



TABLE 3. 

 Comparison of Eastern and Western Specimens of Asymmetron. 



1 Records for the eastern specimens as given by Cooper (1903, p. 348), and hy 

 runnett (1903, p. 362). 



'^ Records for the western specimens as given by Andrews (1893, p. 242). 



