siPHOxoa 



SIPHONOSTOMA. 



7.2 



four distinct joint*. The feet are furnished with long plumose 

 bristles ; and tlie bdomrn is terminated by two small plates directed 

 backwards, and carrying no lateral appendage*. [CAI.IUUS.] 



J>Wari<UM. The small Crustacean* collected by H. Milno Kit wards 

 under this name, are remarkable for the lamellar prolongations with 

 which the upper part of their thorax is furnished. These appendages, 

 he observes, often resemble the elytra of insects, and their number 

 is sometimes considerable; there may be as many as three pairs 

 counted. In general the head is less enlarged and less clypeiform 

 than in the Culiyiani, and the feet are only rarely furnished with 

 plumose setic ; their terminal oars arc often only represented by folia- 

 ceous sub-membranous lobes ; and the abdomen frequently presents 

 on each side of its terminal piece a more or less projecting lamellar 

 appendage. 



M. Milne-Edwards subdivides this tribe into two small groups, 

 principally characterised by the general form of the body, and by the 

 disposition of the oviferous tubes, which in the one are exposed and 

 extended in a straight line behind the body, whilst in the other these 

 tabes are coiled upon themselves, and hidden between the superior 

 surface of the abdomen and a clypeiform lamina which springs from 

 the last thoracic ring. 



The genera k'uryi>lionu, Dinemoura, Pandarut, and Pkyllophora, form 

 the first of these groups. Cccropt and Lrmariut belong to the second. 



Pkyllojihora is very remarkable from the lamellar appendages with 

 which its back is covered. In its aspect it approaches the Autliosomes, 

 but in the structure of its feet and in its general organisation it is not 

 separable from the Paudarians. The only species known is P. cornuta. 

 Length about ten line?. It is taken near Tongataboo. 



eortiula (Milne-Edwards.) 

 a, seen from below. 



Packfcepfiala. In this division of the order ftj'Aonoifonia H. Milne- 

 Edwards describes the head as not enlarged, but lamellar and clypei- 

 form, as in the preceding family, and the antenna?, instead of being 

 abort, flattened, and biarticulnte, as slender, cylindrical, elongated, 

 and composed of five or six joints, the size of which diminishes 

 gradually from the base towards the point of the organ. It is also 

 to be noted that the apparatus of suction is in general less developed 

 in these Crustaceans than in the Peltoccphala, and the mode of con- 

 formation of these appendages, which would appear to represent the 

 jaw-feet, is less constant ; the feet are not soldered on the median line, 

 and consequently do not constitute unequal fins, as is often the case 

 in the preceding family. 



M. Milne- Edwards divides the Pachycephala into two natural groups, 

 the Krgasiluins and the Uichelestians : the first, he observes, estab- 

 lishes the passage between Cyclopt and the Lerntridie; the second, 

 between these last and the Pondarians. 



Ergatitiani. This small group closely approximates to Cyclopt, and 

 is remarkable for the pyriform conformation of the body, the size of 

 the head, and the development of the abdomen. The genera are 

 Eryatiliui, Momoloctu, and Nicothaa. Species of Ergatiliu* are found 

 attached to the gills of the pike and carp (K. HMdii); to those of 

 the eel (K. yiMm); and to those of a SUurtu (K. Iritetaeeiu). The 

 only specie* of Bomolwta known (li. Relona) is found attached to the 

 branchial of the garfish (Kiox llelone). Nicothoa includes but one 

 species (N. Attafi) which is of a rosy colour, about a line in length, 

 and is found upon the bronchia- of the lobster. The young fiicolho<r, 

 on leaving the egg, resemble the young of Cyclop, and want the 

 thoracic lobes, which, when they are adult, give so strange an aspect 

 to these animals. 



. -Tills tribe is cosily distinguished from tbo ErgaM- 



lisns by the elongated form of tha body, the smallness of the head, 

 and the frequently rudimentary state of the abdomen. It is also 

 worthy of note that their feet are much less developed than in the 

 Ergssiliaus, and that the organs by the nid of which they fix them- 

 selves on their prey are, on the contrary, more developed, announcing 

 a more essentially parasitic life. The genera snAnthoioma, Didwlct- 

 tinm, Nemait, Lamproglena. 



But one species of Anlhoioma is known (A. Smil/iii), about ten 

 lines long, and found upon a Squaluf. M. Milne-Edward* remarks 

 that the t'aligui crauut of Abildgaard much resembles this species, 

 but seems to be more stout about the head, and to have the cephalic 

 buckler wider forwards. 



Diclulutium comprises but one species (I). Slurionit). It is about 

 one inch in length, and fixes itself on the branchial apparatus of the 

 Sturgeons. The thorax is divided into four portions in the male, and 

 into five in the female, by interannular divisions. The abdomen is 

 very small in the female, about half as large as the last thoracic ring 

 in the male. Neither does Lamproglena include more than one species 

 (L. pulchrlla), which is found on the gills of the chub. 



M. Milne-Edwards states that it is not without doubt that ho 

 has arranged the Pycnoyonitite in this place, with the Sip/wnoitoma. 

 Amongst the Suctorial Crustaceans, according to M. Milne-Edwards, 

 are the Pycnogoniilir, or Araneiform Crustaceans, as they have been 

 considered by the greater part of zoologists as belonging to the class 

 of A rachmla, but which seem to him to have more analogy with the 

 Criutacea, for they have no trachea) nor pulmonary sacs for aerial 

 respiration, and appear to respire oxygen beneath the water only by 

 means of the general surface of the common teguments, aa he had 

 already pointed out in many inferior Crustaceans. 



In the general form of the body these animals approach the Lanno- 

 dipoda, and especially C-yamut. Their head is elongated, sometimes 

 cylindrical, sometimes conical, and presents at its extremity a trilo- 

 bated buccal orifice. The thorax is constantly divided into four 

 segments, and the abdomen is only represented by a small tubular 

 joint fixed to the posterior edge of the last thoracic ring. The head 

 carries no appendages, and the eyes, four in number, arc grouped on 

 a small median tubercle, situated on the dorsal surface of the first 

 joint of the thorax. This segment often carries at its extremity a 

 pair of jaw-feet terminated by a well-formed pincer, and sometimes 

 furnished with a palp, which is elongated, and composed of many 

 joints. In the male the number of pairs of feet is equal to that of 

 the joints of the thorax ; but in the female there is a pair of pedi- 

 form supplementary appendages fixed to the first joint of the thorax, 

 bent bock under the feet properly so called, much smaller than them, 

 and serving to carry the eggs. The feet are very long, directed out- 

 wards, and composed of nine joints, the last of which constitutes a 

 more or less sharp claw. 



The digestive tube traverses the body in a straight line, and presents 

 in one of the genera of this family (h'ymphum) a very remarkable 

 disposition ; it gives origin, to the right and left, to a series of pro- 

 longations, which am tubular and closed above, which advance very 

 far in the interior of the corresponding feet, and which are the seat 

 of a peristaltic motion. There exists besides a vague circulation. No 

 trace of respiratory organs is perceptible, and the disposition of the 

 organs of generation is not known ; it is only to be remarked, that in 

 the Pycnogonida may be perceived, on the second joint of the posterior 

 feet, a pore, which seems to be the orifice of this last apparatus. 



The Pycnogonida are all of small proportions, and live in the sea ; some 

 are found under stones, others live, it is said, hooked on to fish or other 

 marine animals ; but otherwise nothing is known relative to their habits. 



The genera are Xymphum, Pallene, Phojicliilidium(Oryfhia,Jo\iu- 

 ston), and 1'ycnogonuin. 



Our limits will only allow us to illustrate this group, which still 

 requires the close attention of the physiologist and comparative 

 anatomist, by one genus. Pycnogonum is distinguished from its con- 

 geners by the stoutness of its form, and the size and shortness of its 



litforalr, magnified. 

 a, foot of the same, more highly magnified. 



feet, which are strongly contrasted with those of Nymphum gracite. 

 Only one specie] appears to bo known, I'ycnoyonum liltoratc. The 



