General Morphology. j \ 



In Anelasma squalicola, a Pedunculate Cirripede, parasitic on the Selachian genus Spina x, 

 an important resemblance to the Khizocephala is found in the possession of a root system, 

 springing from the region of fixation, which penetrates into the flesh of the shark and pro- 

 bably serves to nourish the parasite, since the cirri and mouth-parts show marked signs of 

 degeneration. The gnt although it appears to be usually devoid of food does not show any 

 distinct signs of degeneration. 



The root system of Anelasma which springs from the whole surface of the greatly swollen 

 peduncle and ramifies in the tissues of the host, bears an extraordinary resemblance to that 

 of the Khizocephala, both in general appearance and minnte structure. On Piate 2 fig. 3 is 

 presented an optical section through some roots of Anelasma squalicola, with which the Fig. 2 

 on Piate 3, representing some roots of Sacculina, should be compared. In both cases we have 

 an external chitinous investment {eh), beneath which lies a regular epithelium (ep), while the 

 interior of the roots is occupied by a lacunar tissue of branching vacuolated cells (lac). The 

 lacunar cells of the Rhizocephala are less filamentous and more pronouncedly vacuolated than 

 in Anelasma. 



In the Rhizocephala the lacunar tissue of the roots is continuous through the ring of 

 attachment with the connective tissues of the mantle and visceral mass. 



Similarly, the roots of Anelasma are connected with a ramifying lacunar tissue in the 

 Peduncle which surrounds the ovary, in the manner shown on Piate 2 fig. 4 lac. This lacunar 

 tissue is largely developed throughout the Anelasma body, and through it the nourishment 

 absorbed by the roots may be distributed to ali the organs besides the ovary. 



There is moreover a very peculiar fact relative to the ovary in Anelasma which has 

 not, to my knowledge, been described in any other Cirripede, and may very possibly be 

 connected with the method of nourishment by roots. At the edges of the ovary it can be 

 seen that certain ova have migrated out of the ovary and are beginning to degenerate, the 

 nuclei becoming swollen and irregular in shape and diffusing their chromatin into the sur- 

 rounding cytoplasm (Piate 2 fig. ^ov.deg). These degenerating ova can be traced from the edges 

 of the ovary right into the substance of the mantle, whither they must have actively migrated ; 

 and ali through the substance of the mantle, even at the points most remote from the ovary, 

 these wandering ova can be observed in large quantities at various stages of degeneration. A 

 section through part of the mantle is shown in Fig. 5 Piate 2, where some of the degenerate 

 ova are shown in a high- power drawing, from which it is seen that the nucleus may break 

 up into several pieces in one ovum. It must be remarked that this phenomenon is quite 

 different to the normal distribution of the ovary into the mantle which occurs in many 

 Cirripedes ; it appears that here, owing to the surplus of nourishment supplied to the 

 ovary and peduncle by the root system, certain of the ova actively migrate into the tissues 

 of the body to serve as nourishment. It seems, therefore, certain that the chief method 

 of nourishment in Anelasma is by means of the root system, either directly or indirectly by 

 these ova. 



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