The study of teratological fossil specimens may provide important information on the timing and sequence of morphogenesis. For example, Smith and Arbizu (1987) documented inverse larval development in a teratological specimen of a Devonian edrioasteroid.

Probably 90 percent of extant mammals are already known (Goto, 1982), while extinct ones are continually being discovered. Seldom, if ever, has there been an analysis of the approximate rates of discovery of extinct genera per order. Specialists work within their groups and seldom see how their orders compare with those outside their specialty. Questions about intensity of research (on a given order), splitting versus lumping, and general collective interest in an order can partly be answered through a comparative analysis with other orders.

The ichnogenus Desmograpton Książkiewicz, 1977, is described for the first time from the Paleozoic. The ichnogenus has previously been noted from strata of Mesozoic age in Europe and North and South America (e.g., D'Alessandro, 1980; Książkiewicz, 1977; Macsotay, 1967; McCann and Pickerill, 1988). This new occurrence is also significant because it extends the geographic range of Desmograpton into Britain.

Procedures for the use of the nontoxic sodium polytungstate for heavy mineral separations in the study of conodonts or heavy minerals have been described by Callahan (1987), Krukowski (1988), and Savage (1988). These procedures are rapidly being adapted in industrial and university laboratories because they are easy to apply, provide excellent results, and avoid the potential toxicity of most heavy mineral separation mediums. However, the settling time required for most described techniques using sodium polytungstate solution (sp. gr. 1.0-3.1 gcm-3) is considerable and most of the fluid is not immediately reusable. Thus, large quantities of this expensive fluid are required to process multiple samples. Merrill (1987) described the cryogenic density separation of conodonts, noting the rapidity of the technique. The purpose of this paper is to describe modifications of the cryogenic technique. These modifications allow immediate reuse of unwashed portions (80-95 percent per sample) of the heavy medium (thus requiring smaller amounts of the heavy fluid) and increase the rapidity of the technique, especially when separating larger samples (7-25 g).

During the course of fieldwork by a joint Argentine-American expedition to Seymour Island (Elliot et al., 1975) during the austral summer of 1974-1975, a number of brachiopods were collected from the Late Eocene La Meseta Formation. A representative collection of these brachiopods was sent to E. F. Owen, Department of Palaeontology, British Museum (Natural History) for study. Owen (1980) published a revision of the brachiopods from Seymour and nearby Cockburn Islands. The study was based on material collected by W. N. Croft of the Faulkland Islands Dependencies Survey (now British Antarctic Survey) and the material which I sent.