62 BULLETIN OF THE BUREAU OF FISHERIES. 



jelly-fishes known as ephyrse. These in turn pass by an insensible metamorphism 

 directly into medusa?. Direct asexual budding from the adul' medusae is very rare 

 in this class, though quite common in the former. Here the medusa seems the pre- 

 dominant phase in the life history, while (mite the reverse is frequently the case with 

 the Hydromedusae, where the hydroid is often large, long lived, and conspicuous, 

 the medusa small, rudimentary, or entirely suppressed. 



The following morphological characters are usually sufficient for the distinction 

 of the two classes: 



1. Absence of a true velum. The velarium of the Cubomedusae has important 

 structural differences, though doubtless serving essentially similar functions. 



2. The sexual organs and products of entodermic origin. 



3. Gastric filaments usually distinct. 



4. Sense organs, when present, are perhaps modified tentacles, known as tentac- 

 ulocysts, or rhopalia. 



There are four clearly distinguishable orders of Scyphomedusse, characterized 

 as follows: 



I. Stauromedus2E. — Vasiform or subcorneal umbrella. The medusa sedentary in some cases, 

 attached by an aboral peduncle or stalk. Wholly devoid of sensory organs, but provided with 8 

 tentacles or tentacular organs which serve as anchors. Stomach with 4 wide gastric pouches, which 

 communicate with a marginal canal. Gonads in four crescentic loops on the rioor of the gastric 

 pouches. 



II. Peromeihs.k. — Umbrella more or less conical in shape and with usually a well-developed 

 horizontal constriction which divides the body into two regions — an aboral, which often resembles 

 very much the apical projection of many Hydromedusae; and a basal or marginal portion, which is 8 

 or 16 lobed and bears tentacles and rhopalia. Stomach capacious, with 4 gastric pouches which are 

 separated by narrow septa and extend into a circular sinus. Gonads much as in the former order. 



III. Cubomeiu's.k. — A distinctively quadrate body or umbrella, which is provided witli a definite 

 velarium supported at the radial angles by thickenings or frenula?. Marginal tentacles 4. tnterradially 

 disposed, their bases often provided with wing-like expansions known aspedalia; rhopalia 4. perradially 

 disposed. 



IV. Discomedus.e. — A shallow, or disk-shaped, eight-lobed umbrella. Marginal sense organs 

 8, per- and interradiaHy disposed about the margin. Tentacles often very numerous. Manubrium 

 frequently large and with pendulous oral lobes variously plaited or crenulated. Stomach usually 

 large, with 4 to 8 or more gastric pouches, within which the sexual organs are borne in gastrogenital 

 pockets. 



The medusa? of this order are often of large size, many specimens of ( 'yanea reaching a diameter 

 of 3 to 4 or even 6 feet and having tentacles of 50 to 60 feet or more in length when fully extended. 

 The average size, however, even in this genus, is generally much smaller. 



By far the greater. number of Scyphomedusa? are members of this order, as will lie seeti in the 

 following list of genera and species found within the'region under discussion; and this is true of other 

 regions as well. 



STAUROMEDUS*. 



Tessakid.e. — Margin of umbrella devoid of lobes or anchors, apex attenuated into a hollow stalk, 

 which in certain genera serves as a means of attachment; tentacles s, 4 of which are perradial and 4 

 interradial. 



So far as known to me, no representatives of this family come within this region. 



Lucernariid.e. — Margin of umbrella definitely lobed, each lobe terminating in a tuft of delicate, 

 knobbed tentacles. Exumbrella attenuated at the apex as an organ of attachment; margin of umbrella 

 with 8 tentacles, arranged as in the preceding family, but in some cases modified as anchors. 



