642 SUMMARY OF CURRENT RESEARCHES RELATING TO 



After describing tlie (7?/pm-larval forms, tlie author passes to the 

 male of Scalpellum regium, where the microscopic body consists of an 

 elongated sac, closed on all sides ; there is only a very small cleft 

 between the two scuta ; the tentacles are the only appendages which still 

 show their primitive form ; the feet are functionless and straight, and 

 the gnathites have disappeared. In young males the cement-apparatus 

 is well developed, but in mature forms it is not so distinct ; the 

 enteron is aborted and functionless, and no signs of circulatory or 

 respiratory organs are to be detected. The nervous system consists 

 of a rather small cerebral ganglion, a comparatively feeble oesophageal 

 ring, and a large ventral ganglion ; the peripheral nerves are not 

 well developed, and there do not seem to be any eyes, or other sensory 

 organs. The generative system is the only one which is well 

 developed, and of it only the male organs ; even these are much 

 more concentrated than in ordinary hermaphrodite Cirripeds ; there 

 is only one testis, which has the form of a compressed gland, and 

 the seminal vesicle is single, instead of being double. In all 

 these points the small males of other deep-sea species agree with 

 S. regium. 



In the genus Scalpellum Dr. Hoek distinguishes three stages of 

 sexual differentiation. 



I. True hermaphrodite species, all members of which have both 

 female and male genital products ; they are probably self-fecun- 

 dating. Ex. S. halanoides. 



II. Species with large hermaphrodite members, and small males ; 

 the latter may {S. mllosum), or may not (<S^. vulgare) have a stalk, a 

 mouth and a stomach. 



III. Species with the sexes separate; the females large, the males 

 small, and, probably, short-lived ; e. g. S. regium. 



The Cirripedes are rich in organs of an unknown, or at least 

 problematical function, and those first discussed are the " Segmental 

 organs " ; these were regarded by Darwin as being sensory in func- 

 tion, but Hoek ascribes to them the duty of excretory organs : he is 

 supported in this view by the presence of muscular fibres connected 

 with the numerous lacunae, similar to those seen by Grobben in the 

 region of the antennary gland of the Decapoda. 



The cement-glands are next discussed ; and then the " true 

 ovaries " of Darwin, which Hoek looks upon as having a function in 

 relation to the digestive tract, though it is clear that they are not 

 salivary glands ; they probably approximate to pancreatic or hepatic 

 cells. 



The eye of a Cirriped was first seen by Leidy, who described the 

 two small lateral eyes of Balanus ; Dr. Hoek describes the eye of 

 Lepas, and points out that there are certain points of resemblance to 

 what Leydig has described in insects. 



The paper concludes with an account of the female generative 

 organs ; the apparatus which is found at the end of the oviduct 

 possibly represents a second segmental organ ; the sac is regarded as 

 representing the infundibulum of the primitive segmental organ, and 

 it is no objection against this homology that it serves for the 



