2. Life History of D. currata. ^ ( j J 



differentiated males and females, that fertilization takes place in this free-swimming larval 

 stage, and that the fertilized female Cryptoniscus larvae fix themselves on the Rhizocephala 

 and develope into the adult females, while the larval males die without further development. 

 This is an entire misconception. All the Cryptoniscus larvae are hermaphrodites which at 

 first, while they are free swimming, perform the function of males, depositing their copious 

 sperm into the spermathecae of the fixed adults: these free-swimming larvae, after functioning 

 as males, fix themselves to a Rhizocephalon and henceforth function as females. "We have 

 in fact a perfect instance of protandric hermaphroditism with cross -fertilization: and this is 

 in accord with what we know of all the Epicarida see Bonnier 5). In the literature on 

 the Liriopsidae (references to which will be found in Bonnier's book) continual mention is 

 made of larval males; this is perfectly correct but it must be borne in mind that these larval 

 males are only protandric hermaphrodites which will subsecpaently develope into the adult 

 female parasites. 



To the proof of this we now turn. 



2. Life History of D. curvata. 



(Plate 7 figs. 22—30.) 



The larvae, after being hatched out of the body of the parent, go through a series of 

 changes in the free-swimming state which I have not followed, and then assume the Crypto- 

 niscus form which is figured on Plate 7 figs. 22 and 23. With the external form of this 

 larva we need not further concern ourselves, as it is already well known, but a careful eluci- 

 dation of its sexual nature is necessary. The larvae at this stage have been found crawling 

 upon the surface of the body of Sacculina neglecta or upon Inachus scorpio near the point of 

 attachment of the Sacculina: and in a few cases I have found Cryptoniscus larvae crawling 

 upon an adult Danalia curvata which they were no doubt in the act of fertilizing. The sexual 

 nature of these larvae, whether found upon Sacculina, Inachus or Danalia, is always the same; 

 they are all hermaphrodites in which the testes are already mature and the ovary immature. 

 The hermaphrodite gland is a large paired structure lying in the anterior dorsal part of the 

 body (fig. 22 Plate 7 ov and t). A section through the middle of the body and the herma- 

 phrodite gland is shown in fig. 24 Plate 7. The gland in this region is a large testis which 

 always contains a quantity of spermatozoa. The spermatozoa are rod-like organisms of the 

 form shown in Fig. 24 a. At the ventral internal border of the testis is a group of cells (») 

 some of which are large, vacuolated and with consjficuous nucleoli, while others are still small. 

 These cells are a part of the testis and their function is to absorb the remains of that organ 

 after fixation when it is no longer of use. I call these the "phagocytic cells*'. At the extreme 

 anterior end of the gland a very small ovary is visible (ov fig. 22 . 



