473 



PSEUDOBDELLA. 



PSITHYRUS. 



474 



iu thickness from the base to the apex. Thorax usually not much 

 broader than the head, sometimes nearly cylindrical, but most com- 

 monly dilated in the middle ; elytra broad, much shorter than the 

 abdomen, and truncated behind, destitute of stria;, if we except one 

 on each elytron near the suture, and an abbreviated stria at the base 

 about mid-way between the suture and the outer margin these are 

 almost constant. Abdomen broad, obtusely terminated, and without 

 appendages as observed in the Brachelytra ; usually four or five jointa 

 are visible beyond the elytra. Legs rather long ; tibiae curved ; tarsi 

 3-jointed, the basal joint small, and the terminal joint furnished either 

 with one or two simple claws. 



The Pidaphidce are composed of the following 13 genera, which may 

 be most briefly characterised by throwing them into a tabular form, 

 as in M. AUDI'S Monograph, published in Guerin's ' Magasin de 

 Zoologie ' for the year 1834. 



Section 1. Antenna; two-jointed. 

 Division 1. Tarsi with two claws. 

 1. A. with the claws unequal. Metopiai. 

 1. B. with the claws equal. Tj/rtu, C/iennium, Ctenwtea. 



Division 2. Tarsi with a single claw. 



Ptdaphui; BrycLcit ; Tychiu ; Sylhinus ; Trimium; Botritta; 

 tta. 



Section 2. Antenna; six-jointed. 

 Claviger. 



Section 3. Antenna; with but one large and elongated joint. 

 Articerut. 



Examples of most of these genera are found in this country. Of 

 the genus ifetopiat only one species is known ; it inhabits Guyana. 

 The genus Tyrus is found in Sweden and Germany, and perhaps in 

 England. Of the genus Ckennium but one species is known : it is 

 found in the south of France. The curious genus Claviger has been 

 discovered in England by Mr. Westwood : it is found in the nest of 

 a species of ant (Formica Jtava). On the Continent it has been long 

 known. 



Owing to their remarkable appearance, and the curious forma dis- 

 played by the various species, the Ptdayhiduc have been more carefully 

 studied perhaps than any other group of minute insects, and have given 

 .rise to several monographs see the ' Monographia Pselaphidorum et 

 Seydrnamidarum Britannia;,' by H.Denny, Norwich, 1825, 1 vol. 8vo. ; 

 ' Monographia Pselaphorum,' H. F. L. Reichenbach, Lipauc, ISHi, 

 1 vol. 8vo. P. W. J. Miiller has published a monograph on the Ptelaphi 

 in the third volume of the ' Magazin der Entomologie, von E. F. 

 Germar.' M. C. Aub<5 has likewise published an excellent monograph 

 on the same group, which has been quoted in the former part of this 

 article. 



P.SEUDOBDELLA. [ANNELIDA.] 



PSEUDOCA'RCINUS, M. MUne-Edwards'a name for a genus of 

 Crustacea. 



The general form is that of many Xantlti. [XANTHOS.] The carapace 

 is slightly convex, and a little embossed near the front, which is 

 nearly horizontal ; latero-auterior borders moderately curved, and 

 armed with more or less projecting teeth ; posterior portion of the 

 carapace nearly of the same extent as the anterior, with its lateral 

 borders straight, and directed very obliquely backwards. The baailary 

 joint of the external antenna; is very small, the second hardly reaches 

 the front, and the third, which is lodged in the orbital gap, does not 

 fill it, so that the auteunary fosset is not completely separated from 

 the orbit ; the terminal t=m of these appendages, instead of being 

 very short, is more than twice us long as its peduncle. The species 

 are found in the Indian and Southern Oceans. 



P.SEUDOCORYSTES, M. Milne-Edwards's name for a genus of 

 Erachyurous Crustaceans belonging to his tribe of Corystians, and 

 bearing much analogy to Coryttet [CoRYSTEs], and especially to Nau- 

 tilocoryte. 



General form approximating to Corystes, but the feet natatory, as in 

 NauMocorystei : jaw-feet differing from those of both. 



PSEUDOGRAPSUS. [GBAPSID*.] 



PSEUDOLI'VA, a genus of Gasteropoda. 



PSEUDOPODIA. [INFUSORIA.] 



PSEUDORHOMBILA. [QONOPLACIT.E.] 



PSEUDOZOA'RIA, a term proposed by De Blainville to include 

 plants, many of which have been ranked with the Polypiaria. It is 

 subdivided into two classes : C'alciphyta, which are principally com- 

 posed of the genus Condlina, Linn.; and Nematophyta (also called 

 JVematozoaria), which include Conferra, Osciltatm-ia, Bytsus, &c. [Aw J! ; 

 COBALLINACE.&] 



PSI'DIUM (from if'/Sioc, the Greek name for a pomegranate), a genus 

 of Plants belonging to the natural order Myrtaceie. The tube of the 

 calyx is ellipsoid or obovate, usually contracted at the apex ; the 

 liinb ovate, undivided, but afterwards from 1- to 5-cleft. There are 

 fivo petals and numerous free stamens inserted in a broad circle, almost 

 through the whole undivided part of the limb ; the style is filiform, 

 the stigma capitate ; the ovulaa are numerous, horizontal, and fixed to 

 the margin of the placenta; the berry is many-seeded, corticate by 

 the tube of the calyx, and crowned by its lobes. The seeds imbedded 



in the pulp in the mature fruit with a bouy testa. The species are 

 trees or shrubs, natives of America within the tropics. The fruit is 

 edible, and is known by the name of Guava. It haa a fragrant but 

 peculiar odour and very sapid taste, and is eaten both raw and when 

 made into jelly. 



P. pomiferum, Apple-Bearing or Common Red G uava, has tetragonal 

 branches, oval or oblong lanceolate leaves, pubescent beneath, from 

 3 to 8 peduncles, or many-flowered. The fruit is globose, yellow, and 

 somewhat astringent, with an agreeable odour ; the root and young 

 leaves are astringent; and are esteemed strengthening to the stomach. 

 It is a native of the West Indies, Mexico, and South America. 



P. montanum has tetragonal branches, oval-oblong leaves, acuminated 

 and quite glabrous ; the peduncles many-flowered, and the fruit 

 roundish. It is a native of Jamaica on the mountains. The fruit is 

 small, acid, and smells strongly like bitter almonds, hence it is c died 

 Alinandron. The wood is very hard and of a fine colour and grain. 

 It works well, takes a fine polish, and is much esteemed for orna- 

 mental purposes. 



PSILLOSTOMATINA. [CHEIROPTERA.] 



PSILOMELANE. [MANGANESE.] 



PSILOPOGON. [PICID.E.] 



PSILOSO'MATA, M. De Blainville's name for his third family of 

 his order Aporobranchiata, and placed by him at the end of that order 

 and immediately before the order Pvlybranchiata, which contains the 

 genus Carolina. [POLYBRANCHIATA.] 



The only genus of Pailosomata recorded by M. De Blainville is 

 Phyllirue. 



Body free, naked, very much compressed, or much higher than it is 

 thick, terminated behind by a sort of vertical fin ; cephalo-thorax 

 small, and provided with a pair of natatory appendages, which are 

 triangular, compressed, and simulate a kind of long tentacles or 

 brauchije ; mouth subterminal, of a horse-shoe shape, with a short 

 retractile proboscis ; anus on the right side of the body ; orifice of the 

 organs of generation unique, on the same sido, and more anterior than 

 the anus. Organs of respiration ( ? ). 



Ex. Phyllirhoe Bucepltalum. 



This species was discovered iu the Mediterranean Sea by PcSron and 

 Lesueur. 



PSI'THYRUS, Saint Fargeau, a genus of Hymenopterous Insects 

 belonging to the section Antkophila (Latreille) and family Apidce, 

 The insects of this genus so closely resemble the Humble-Bees 

 (Jiombui), that till recently they W( re by all authors confounded with 

 them. The Ptithyri however differ widely from the Humble-Bees, 

 inasmuch as they make no nests of their own, neither do they collect 

 food for their young, but, like the Cuckoo among birds, they deposit 

 their eggs in the nests of others, and leave their young to be hatched 

 and reared by them. It is the nests of the Humble-Bees that they 

 select for this purpose. Mr. Newman considered these facts relating 

 to their economy so important, that he established an order among 

 Hymenopterous Insects, to which he gave the name Apathites (trom 

 a, without, and iraSos, affection), for the reception of the present 

 insects, which, according to him, constitute the genus Apalkus, and 

 gome other genera of bees. The characters of the order Apathites, 

 given by the author, are as follows : Larva hatched froin an egg, 

 deposited by its parent in the nest of other Apid(e at the time when 

 their own eggs are laid ; when it hatches, being stronger and larger 

 than the rightful possessor of the cell, it consumes the food provided 

 for its companion, and starves it to death ; and iu those instances iu 

 which fresh supplies of food are daily provided, it continues to receive 

 and appropriate them as its own. Pupa changes in the same situation, 

 in a silken cocoon, spun by the larva. Imago has no apparatus either 

 on the body or legs for collecting honey; in othur respects it resembles 

 in structure each of the other orders of Apid<e. It enters their nest 

 with perfect familiarity, and seems to bo quite unsuspected of 

 intrusion. It collects no pollen or honey, never builds a nest of any 

 kind, nor takes any care of its young, but spends its time among 

 flowers, or hovering about sand-banks in which other bees have fixed 

 their habitations. The genera included in this order are Apatkus 

 (or Psitkyrus), Cadioxyt, Melecta, Stelis (?), Epeolus, Nomada, and 

 Ilylaus (?). ('Entomological Magazine,' vol. ii. p. 404.) The order 

 Apathites however is very objectionable in many points of view; it is 

 founded upon the habits of the species, whilst in tact the habits of the 

 individuals composing the very genera placed by the author in his 

 order are in many cases but partially known : the order moreover 

 comprises genera agreeing in no positive points of structure. 



The species of the genus Psilhyrus may be distinguished from 

 those of Bornbus by the structure of their hinder legs. In Bombua 

 the hinder tibia is compressed, smooth, and somewhat concave on the 

 outer side, and is furnished on its edges with a fringe of stiff 

 curved hairs, which serve to retain on the outer side of the shank the 

 pollen collected by the insect to feed its young. The PiUhyn have the 

 tibia narrower and covered throughout with hair. They have no 

 baket for the purpose of carrying pollen. 



Four or five species of Piithyrus are found in England, and these 

 are well described by Kirby iu his 'Monographia Apum Angliao.' They 

 are arranged by that author in his genus Apis, section **, c. 2, which 

 section also includes the true Bombi. 



Peithyrut rupotrii very closely resembles the Red-Tailed Humble- 



