ON SOME PLY]\rOUTH HOLOTHURIANS. 223 



as the Plymouth species known at that time at Plymouth as C. planci, 

 while the other two, B and C, were similar to the species known at that 

 time at Plymouth as C. pentactes. After discussing the synonymy of 

 Norman's C. montagui, Pace showed (1) that this name is a complex one, 

 whose original form could not be traced, (2) that C. j^^cinci Brandt 

 " cannot be applied to the very different species from Plymouth," and 

 (3) that C. pentactes (Linnaeus) " is now generally regarded as an in- 

 determinate species." He therefore proposed to abolish all these names, 

 substituting C. normani for the Plymouth C. planci and specimen A of 

 Norman's C. montagui ; and C. saxicola Brady and Robertson for the 

 Ph'mouth C. pentactes, and B and C of Norman's C. montagui, which were 

 shown to be identical with a species described in 1871 by Brady and 

 Robertson as C. saxicola. 



The researches here described support Pace's contention that Norman's 

 C. montagui consisted of two species, subsequently named by Pace as 

 C. normani Pace, and C. saxicola Brady and Robertson. 



In 1905 Norman (2) wrote a paper maintaining his former views, 

 which at this stage can be stated to be as follows : That he considered 

 the Plymouth C. saxicola as the young of the Plymouth C normani Pace, 

 and that both were really equivalent to C. montagui Fleming. Norman's 

 main contention in this paper is that the Plymouth C. saxicola are the 

 young of the Plymouth C. normani. He, however, freely states that 

 " When young specimens of C. montagui, say 14 mm. long, should be 

 found having spicules agreeing with those of the adult, my view that B 

 and C are young forms of that species would require to be reconsidered." 

 In further support of his view Norman cited the known facts that spicules 

 found in the young of some forms (for example, C. frondosa) disappear 

 in the adult, and that spicules which in the young of some forms are 

 smooth (for example, C. liyndmanni) become nodulous or thickened in 

 older specimens. 



The correlation of differences in the gonad and calcareous collar with 

 the differences in the spicules described above is doubtless sufficient to 

 establish the distinctness of these two species. Fortunately, however, 

 tiny young ones of both species have been obtained, and so enable a 

 comparison of both forms to be made throughout all stages of growth. 



Besides these, however, De Morgan also obtained tiny C. normani. 

 In his unpublished MS. he states : " I have examined specimens of 

 both species from about one centimetre to three inches in length, both 

 fresh and preserved in spirit, and find the plates that distinguish C. 

 normani confined to C. normani ; and those of C. saxicola to C. saxicola.^' 



