110 THE VOYAGE OF H.M.S. CHALLENGER. 



a less extent. The ovaries of the Peutacrinidas are likewise long and fusiform, some of 

 them a2)pearing to present somewhat anomalous characters. For in some sections which 

 were made for Sir Wyville Thomson by Dr. Stirling, the ovary appears in the arm, 

 occupying the usual position between the subtentacular and the cceliac canals where the 

 sterile genital cord is normally found. This is also the case in the lower parts of the 

 arms of Holopus (PI. Vc. fig. 2, ov), but I have not yet succeeded in discovering which 

 species of Pentacrinus or Metacrinus is distinguished by this peculiarity; for the sections 

 above mentioned were not labelled with any name or reference number. I have cut 

 sections of the arms of all the more common Pentacrinida^, but in none of them have I 

 found any such departure from the type of the ordinary Antedon as is presented by the 

 ovaries of this unknown species. 



Many years since it was discovered by Prof Semper,^ during his residence in the 

 Philippine Islands, that the ovaries of Actinometra parvicirra [ = Actinometra armata, 

 Semper, M. S.) are not attached to the genital cord by their ends in the usual way. For 

 a backw^ard process is given off at the point where the short branch of the sterile genital 

 cord expands into the fertile poi'tion of the gland ; and it lies within the ventral perisome 

 of the arm on the proximal side of the pinnule attachment. This is as fertile as the 

 rest of the gland which is actually within the pinnule, so that the whole structure 

 apjjears to be attached to the genital cord at some little distance from its end ; and it 

 comes right down into the arm at the sides of the subtentacular and cceliac canals, being 

 attached almost directly to the genital cord (the so-called rachis), the lateral branches of 

 whicli are quite short. In most sections of the arms, therefore, an ovary is to be seen on 

 either side of the central genital cord (PI. LXI. fig. 3). 



This condition also occurs in Metacrinus angidatus, and in other Philippine 

 Comatulse, e.g., Actinometra nobilis and Actinometra dissimilis;' and so far as one can 

 judge from the appearance of the ventral perisome, without cutting sections, I suspect 

 that it is tolerably common in the larger tropical Comatulae. 



Although I have examined the ovarian pinnules of a large number of species, I have 

 never met with definite openings for the discharge of the ova ; and I must therefore, 

 like Ludw^ig, leave undecided the question of the origin of the relatively large openings 

 which occur on the inner side of the pinnules of Antedon rosacea at the time of 

 sexual maturity. On the other hand, I have found male indi^dduals in which the 

 testicular openings are evident enough (PI. LIV. fig. 3). In Antedon acoela and Antedon 

 angusticalyx, for example, the fertile part of the gland is short, thick, and rounded. It 

 only extends over four or five of the pinnule segments, and is protected by the tolerably 

 regular pavement of plates already described. At about the middle of its length one or 

 two small conical projections rise from it towards the ventral surface of the pinnule, and 



1 Arh. zool.-zootom. Inst. Tfiirzhirg., loc. cit., fig. 1, p. 261. 



2 a 



2 The specific formula of this type is — a . 3 . ^ . 3 . 3 . y 



