REPORT ON THE SIPHONOPHORvE. 131 



tamed a few detached Eudoxise of this species, which fully developed represent the 

 monogastric Diplophysa kollikeri, Haeckel. 



Sphseronectes may be derived from Monophyes by concrescence of the two parallel 

 crests or wings, which arise from the ventral side of the nectophore. The hydroecial 

 groove of the latter becomes converted by this process into a closed tubular hydrcecium, 

 which includes the siphosome. The cormidia, which are attached to the common stem 

 at regular intervals, possess a subspherical bract with a simple vertical phyllocyst, and 

 detached from the stem represent the genus Diplophysa (compare p. 107). 



Genus 20. Mitrophyes, 1 Haeckel, 1888. 

 Mitrophyes, Hkl., System der Siphonophoren, p. 34. 



Definition. — Monophyidse with a rounded, edgeless, hemispherical or mitriform 

 nectophore, without a true hydrcecium. Trunk free between the exumbrella of the 

 nectophore, and a scutiform or cap-shaped bract, depending from the junction of these 

 two pieces. Bracts spathiform or semi-ovate, without phyllocyst. 



The genus Mitrophyes was founded by me for an Atlantic Monophyid, which I 

 observed living in the Canary Sea, in January 1867. I observed there two complete 

 specimens, a male and a female. A third specimen (female) was found in the Challenger 

 collection, among other pelagic animals from Station 352. The latter specimen was well 

 enough preserved to enable me to identify it with the former. 



Mitrophyes differs from all other Monophyidre in the possession of a peculiar bract, 

 which covers the single nectophore like a shield or cap, and in the absence of a 

 hydrcecium, the trunk depending freely between those two pieces and arising from their 

 junction. It may be compared to a Praya or a similar Diphyid, the first nectophore of 

 which is rudimentary and transformed into a bract. 



Mitrophyes peltif era, n. sp. (PL XXVIII. ). 



Habitat. — Tropical and Northern Atlantic, Station 352; April 13, 1876; lat. 

 10° 55' N., long. 17° 46' W. Surface. 



Canary Islands, Lanzerote, January 1867 (Haeckel). 



Nectophore. — The single large nectophore is nearly hemispherical, somewhat oblique, 

 its nectosac being higher in the ventral than in the dorsal half ; it is 6 to 8 mm. long, 

 4 to 5 mm. high. The voluminous jelly-mantle of the umbrella is twice as thick in the 

 dorsal part as in the ventral. The equatorial diameter of the smooth rounded exumbrella 

 is nearly twice as great as that of the subumbrella, and as the height of the nectophore. 



1 Mitrophyes = Mitrophorous, animal provided with a mitre, fth^ec, Qvi);. 



