xvi GLOSSOLOGY. 



Manubrium {maniihrinw , handle). The axial portion which, in a raedusiform planoblast, 

 hangs from the summit of the umbrella, carrying the mouth at its extremity. (Diagram I, /, and 

 Fig. 8, page 33.) 



Atrium {atrium, a hall). An enlargement of the somatic cavity which occurs in many 

 medusae. It is situated at the base of the manubrium, and from it the radiating canals proceed. 

 (Fig. 17, page 46.) 



Codonostome (kwIwv, bell ; arofxa, mouth). The orifice of the umbrella through which its 

 cavity communicates with the external water. (Fig. 8, page 33.) 



Velum {velum, a veil). The membranous perforated diaphragm which stretches transversely 

 across the codonostome. (Fig. 8, h, page 33.) 



Ocellus (diminutive of oculus, eye). A heap of pigmentncells accompanied or not by a 

 refracting body, and forming a coloured spot on definite points of the umbrella-margin in certain 

 planoblasts. (Fig. 5(3, t;, page 139.) 



Lithocyst {X'Soc, stone ; kiIcttic, bladder). A sack-like body containing concretions, developed 

 on definite points of the umbrella-margin in certain planoblasts. (Figs. 57, c, and 58, //, pages 140 

 and 141.) 



Phanerocodonic {<j>avipoQ, manifest; kuiSujv, bell). The condition of a gonophore when it 

 possesses a developed umbrella. (Diagram I, /.) 



Adelocodonic (aSijXoc, not manifest; kmSwv, bell). The condition of a gonophore when no 

 developed umbrella is present. (Diagram I, I; Ic , and II, k.) 



Gonangium (yo'i-oc, off'spring; a-yytiov, vessel). An external chitinous receptacle within 

 which, in the calyptoblastic genera, the sporosacs or planoblasts are developed. (Diagram II, «.) 



Gubernacidum [ffitbernaculum, rudder, director). A common sack-like membrane which 

 surrounds the generative buds within the gonangium, and aids in directing them or their contents 

 towards the orifice of the gonangium. (Figs 18, d, and 19, d, page 48.) 



Acrocyst {aKpog, on the top ; Kvan^, bladder). An extenial sac which in certain hydroids is 

 formed upon the summit of the gonangium, where it constitutes a receptacle in which the ova 

 pass through some of the earlier stages of their development. (Figs. 21 and 22, page 50.) 



Meconidium (diminutive from /miKuv, a poppy). Peculiar sporosacs, somewhat resembling 

 a poppy capsule in form, and borne upon the summit of the gonangium in the genus GonothyrcBa. 

 (Fig. 28, page 57.) 



Corbulae {corbula, a basket). Basket-shaped receptacles which enclose groups of gonangia 

 in certain plumularian hydroids. (Fig. 30, page 60.) 



Planula (a diminutive noun, suggested by a supposed resemblance to a Planarid). The 

 locomotive infusorium-like embryo into which the egg of most hydroids becomes directly 

 developed. (Fig. 39, K, page 86.) 



Actinula (a diminutive noun found from okt/c, a ray). The locomotive polypoid embryo into 

 which, in certain genera, the egg becomes directly developed. (Plate XXI, fig. 6, Plate XXIII, 

 fig. 16, &c.) 



